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Summary of Significant Accounting Policies (Details 2) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Accounting Policies [Abstract] |  |  |
Minimum adjusted taxable income to be distributed to shareholders to qualify as a REIT (as a percent) | 90.00% |  |
Subsequent period during which entity would be disqualified as a REIT if during any tax year entity fails to qualify as a REIT (in years) | 4 years |  |
Dividends Payable [Line Items] |  |  |
Approximate amount by which basis of assets and liabilities for tax reporting purposes is lower than amount reported on consolidated balance sheet | $ 224 |  |
Common Shares [Member] |  |  |
Dividends Payable [Line Items] |  |  |
Ordinary income (as a percent) | 38.30% | 64.50% | 71.80%
Long-term capital gain (as a percent) | 61.70% | 6.50% | 22.40%
Return of capital (as a percent) | 0.00% | 29.00% | 5.80%
Preferred Shares [Member] |  |  |
Dividends Payable [Line Items] |  |  |
Ordinary income (as a percent) | 38.30% | 90.90% | 76.20%
Long-term capital gain (as a percent) | 61.70% | 9.10% | 23.80%
Return of capital (as a percent) | 0.00% | 0.00% | 0.00%

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- Definition Represents the minimum percentage of adjusted taxable income required to be distributed to shareholders for qualifying as a real estate investment trust. + References No definition available. + Details
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- Definition Represents the subsequent number of years during which the entity would be disqualified as a real estate investment trust, if during any tax year the entity fails to qualify as a real estate investment trust. + References No definition available. + Details
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