Stockholders' Equity (Distribution of REIT Taxable Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Equity [Abstract]
Common and preferred dividends	$ 107,167	$ 99,138	$ 1,077,179
Dividends treated as taxable compensation	(150)	(129)	(92)
Portion of dividends declared in current year, and paid in current year, which was applied to the prior year distribution requirements	0	0	0
Portion of dividends declared in subsequent year, and paid in subsequent year, which apply to current year distribution requirements	0	0	0
Dividends in excess of current year REIT distribution requirements	0	0	(827,005)
Dividends applied to meet current year REIT distribution requirements	$ 107,017	$ 99,009	$ 250,082