Earnings per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator:
Net Income (Loss) Attributable to Parent	$ 32,463	$ 73,975	$ 93,160	$ 161,378
Preferred Stock Dividends, Income Statement Impact	(6,279)	(6,279)	(18,836)	(18,836)
Less: Dividends paid on unvested restricted shares	(342)	(274)	(1,032)	(937)
Less: Undistributed Earnings allocated to unvested restricted shares	0	(46)	0	0
Net income attributable to common shareholders excluding amounts attributable to unvested restricted shares	$ 25,842	$ 67,376	$ 73,292	$ 141,605
Denominator:
Weighted-average number of common shares - basic (in shares)	170,495,699	174,326,198	171,976,429	174,253,393
Unvested restricted shares (in shares)	105,088	129,075	90,044	109,523
Incremental Common Shares Attributable to Performance Units	0	24,068	0	2,185
Weighted-average number of common shares - diluted (in shares)	170,600,787	174,479,341	172,066,473	174,365,101
Net income per share attributable to common shareholders - basic (in dollars per share)	$ 0.15	$ 0.39	$ 0.43	$ 0.81
Net income per share attributable to common shareholders - diluted (in dollars per share)	$ 0.15	$ 0.39	$ 0.43	$ 0.81