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Income Taxes - Federal Income Tax Treatment of Share Distributions (Parenthetical) (Detail) | 0 Months Ended | 12 Months Ended | 0 Months Ended
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Apr. 11, 2013 Series J Preferred Stock [Member] | Dec. 31, 2013 Series J Preferred Stock [Member] | Apr. 11, 2013 Depositary Shares [Member] Series J Preferred Stock [Member] | Dec. 21, 2012 Depositary Shares [Member] Series J Preferred Stock [Member] | Jul. 18, 2013 Depositary Shares [Member] Series K Preferred Stock [Member]
Income Tax [Line Items] |  |  |  |  |
Depositary shares of preferred stock redeemed | 4,000,000 | 2,000,000 | 4,000,000 | 2,000,000 | 2,000,000

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- Definition Preferred Stock Redeemed Shares + References No definition available. + Details
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