Income Taxes (Tax Treatment of Distributions and Consolidated Benefit for Income Taxes) (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
Tax treatment of distributions:
Ordinary income (in dollars per share)									$ 0	$ 0	$ 1.02814
Qualified ordinary income (in dollars per share)									0.12230	0.00375	0.00337
199A qualified business income									2.22898	2.97465	0
Long-term capital gain (in dollars per share)									0	0.05916	1.07836
Unrecaptured Section 1250 gain (in dollars per share)									0.03434	0.12244	0.21513
Tax treatment of non-dividend distributions									0.78438	0	0
Distribution reported for 1099-DIV purposes (in dollars per share)									3.17000	3.16000	2.32500
Common Stock, Dividends, Per Share, Declared, Taxable in Following Year	$ 0.79250									0.79250	0.79000
Less: Dividend declared in prior year and taxable in current year									(0.79250)	(0.79000)	0
Dividends declared per common share (in dollars per share)		$ (0.7925)	$ (0.7925)	$ (0.7925)	$ (0.7925)	$ (0.79)	$ (0.79)	$ (0.79)	$ (3.17000)	$ (3.16250)	$ (3.11500)
Provision (benefit) for income taxes
Current - Federal									$ (1,840)	$ (2,953)	$ (5,672)
Current - State									2,118	1,332	1,119
Deferred - Federal									(49,532)	(32,492)	(54,396)
Deferred - State									(3,353)	(825)	3,237
Current - Foreign									2,335	1,892	2,307
Deferred - Foreign									(6,038)	(6,907)	(6,394)
Income tax benefit									$ (56,310)	$ (39,953)	$ (59,799)