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Capital Stock (Narrative) (Details) (USD $)
In Millions, except Share data, unless otherwise specified |
0 Months Ended | 6 Months Ended | 12 Months Ended | |||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Dec. 01, 2011
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Nov. 18, 2011
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Sep. 01, 2011
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Aug. 15, 2011
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Jul. 12, 2011
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Jun. 13, 2011
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Jun. 01, 2011
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Apr. 29, 2011
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Mar. 01, 2011
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Feb. 15, 2011
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Dec. 01, 2010
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Nov. 19, 2010
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Sep. 01, 2010
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Aug. 13, 2010
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Jun. 01, 2010
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May 14, 2010
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Dec. 31, 2011
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Dec. 31, 2011
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Dec. 31, 2009
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May 25, 2011
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Dec. 31, 2010
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Jun. 13, 2011
Common Shares [Member]
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Jun. 13, 2011
Over Allotment Option Member
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Dec. 31, 2011
Preferred Class A [Member]
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May 25, 2011
Preferred Class A [Member]
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Dec. 31, 2010
Preferred Class A [Member]
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Dec. 31, 2011
Preferred Class B [Member]
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May 25, 2011
Preferred Class B [Member]
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Dec. 31, 2010
Preferred Class B [Member]
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May 25, 2011
Maximum [Member]
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May 11, 2010
Scenario, Previously Reported [Member]
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May 11, 2010
Scenario, Adjustment [Member]
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| Shares authorized to be repurchased | 4,000,000 | |||||||||||||||||||||||||||||||
| Stock repurchased during period, value | $ 289.8 | $ (289.8) | ||||||||||||||||||||||||||||||
| Stock repurchased, cost per share | $ 72.44 | |||||||||||||||||||||||||||||||
| Common shares, issued | 149,195,469 | 149,195,469 | 138,845,469 | 9,000,000 | 1,350,000 | |||||||||||||||||||||||||||
| Closing price per share | $ 85.63 | $ 85.63 | ||||||||||||||||||||||||||||||
| Dividend payable, per share | $ 0.28 | $ 0.0875 | $ 0.14 | |||||||||||||||||||||||||||||
| Proceeds from issuance of common stock | $ 854.0 | $ 853.7 | $ 347.3 | |||||||||||||||||||||||||||||
| Common share dividends date paid | Dec. 01, 2011 | Sep. 01, 2011 | Jun. 01, 2011 | Mar. 01, 2011 | Dec. 01, 2010 | Sep. 01, 2010 | Jun. 01, 2010 | |||||||||||||||||||||||||
| Common share dividends date of record | Nov. 18, 2011 | Aug. 15, 2011 | Apr. 29, 2011 | Feb. 15, 2011 | Nov. 19, 2010 | Aug. 13, 2010 | May 14, 2010 | |||||||||||||||||||||||||
| Percentage increase in dividends payable | 100.00% | |||||||||||||||||||||||||||||||
| Total shares, authorized | 231,000,000 | 407,000,000 | ||||||||||||||||||||||||||||||
| Common shares, authorized | 400,000,000 | 400,000,000 | 224,000,000 | 224,000,000 | 400,000,000 | |||||||||||||||||||||||||||
| Preferred stock, shares included in amendment | 3,000,000 | 3,000,000 | 3,000,000 | 4,000,000 | 4,000,000 | 4,000,000 | ||||||||||||||||||||||||||
| Issuance of common shares (in shares) | 10,350,000 | |||||||||||||||||||||||||||||||