Earnings Per Share and Equity Transactions - Reconciliation of Amounts Used in Calculating Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Income (Loss) Attributable to Parent [Abstract]
Net income from continuing operations	$ 28,694	$ 24,926	$ 6,278	$ 4,001					$ 63,899	$ 83,849	$ 57,954
Earnings allocated to unvested restricted shares									(29)	(95)	(15)
Net income from continuing operations attributable to common shareholders									63,870	83,754	57,939
Net (loss) income from discontinued operations	$ 0	$ 0	$ (12,000)	$ (13,500)					$ (25,500)	$ 0	$ 3,839
Denominator:
Weighted average number of common shares outstanding, basic	728,544,149	728,722,763	728,654,374	728,558,989	727,904,818	768,385,770	774,391,881	774,311,254	728,620,309	761,139,011	773,445,341
Effect of unvested restricted shares (in shares)									763,840	926,463	1,155,138
Weighted average number of common shares outstanding - diluted	729,536,570	729,456,722	729,287,663	728,827,861	728,973,047	769,306,859	774,930,240	774,394,732	729,384,149	762,065,474	774,600,479
Basic and diluted income per common share:
Net income from continuing operations allocated to common shareholders per share (in usd per share):									$ 0.09	$ 0.11	$ 0.07
Net income, per common share, from discontinued operations, basic and diluted (in dollars per share)	$ 0	$ 0	$ (0.02)	$ (0.02)					(0.04)	0	0
Net income per common share, basic and diluted (in dollars per share)	$ 0.04	$ 0.03	$ (0.01)	$ (0.01)	$ 0.03	$ 0.01	$ 0.03	$ 0.04	$ 0.05	$ 0.11	$ 0.07

Undistributed Income (Loss) From Continuing Operations Allocated to Common Stockholders

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Undistributed Income (Loss) From Continuing Operations Allocated to Unvested Shares

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Amount after tax of income (loss) from continuing operations attributable to the parent.

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The amount of net income (loss) from continuing operations per each basic and diluted share of common stock or unit when the per share amount is the same for both basic and diluted shares.

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Amount after tax of income (loss) from a discontinued operation attributable to the parent. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

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Per basic and diluted share amount, after tax, of income (loss) from the day-to-day business activities of the discontinued operation and gain (loss) from the disposal of the discontinued operation, when the per share amount is the same.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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