Condensed Consolidated Statements of Shareholders' Deficit (unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss) Income	Distributions in Excess of Accumulated Earnings	Noncontrolling Interest
Beginning balance, value at Dec. 31, 2017	$ (1,207,142)	$ 17	$ 644,328	$ 7,821	$ (1,960,715)	$ 101,407
Beginning balance, shares at Dec. 31, 2017		174,851,514
Impact of change in accounting standard, net of tax	1,859				1,859
Net (loss) income	1,862				1,838	24
At-the-market issuance of common stock, net of offering costs	64,423	$ 1	64,422
At-the-market issuance of common stock, net of offering, shares		3,180,548
Amortization of discount on convertible preferred stock	(2,235)		(2,235)
Other comprehensive income (loss)	59,850			58,470		1,380
Common stock dividends declared	(318,865)				(318,865)
Distributions to noncontrolling interest	(7,438)					(7,438)
Convertible preferred stock dividends	(1,968)				(1,968)
Net share settlement	(1,575)		(1,302)		(273)
Stock-based compensation	6,058		6,058
Stock-based compensation, shares		178,135
Ending balance, value at Sep. 30, 2018	(1,405,171)	$ 18	711,271	66,291	(2,278,124)	95,373
Ending balance, shares at Sep. 30, 2018		178,210,197
Beginning balance, value at Jun. 30, 2018	(1,374,812)	$ 17	645,627	56,237	(2,174,216)	97,523
Beginning balance, shares at Jun. 30, 2018		175,028,835
Net (loss) income	4,224				4,131	93
At-the-market issuance of common stock, net of offering costs	64,423	$ 1	64,422
At-the-market issuance of common stock, net of offering, shares		3,180,548
Amortization of discount on convertible preferred stock	(745)		(745)
Other comprehensive income (loss)	10,291			10,054		237
Common stock dividends declared	(107,379)				(107,379)
Distributions to noncontrolling interest	(2,480)					(2,480)
Convertible preferred stock dividends	(656)				(656)
Net share settlement			4		(4)
Stock-based compensation	1,963		1,963
Stock-based compensation, shares		814
Ending balance, value at Sep. 30, 2018	(1,405,171)	$ 18	711,271	66,291	(2,278,124)	95,373
Ending balance, shares at Sep. 30, 2018		178,210,197
Beginning balance, value at Dec. 31, 2018	(1,493,203)	$ 18	757,517	30,105	(2,373,218)	92,375
Beginning balance, shares at Dec. 31, 2018		180,535,971
Impact of change in accounting standard, net of tax	(63,222)				(63,222)
Net (loss) income	22,262				21,739	523
At-the-market issuance of common stock, net of offering costs	21,641		21,641
At-the-market issuance of common stock, net of offering, shares		1,176,186
Amortization of discount on convertible preferred stock	(993)		(993)
Other comprehensive income (loss)	(58,758)			(57,557)		(1,201)
Common stock dividends declared	(26,802)				(26,802)
Distributions to noncontrolling interest	(567)					(567)
Exchange of noncontrolling interest			6,540			(6,540)
Exchange of noncontrolling interest, shares		666,576
Convertible preferred stock dividends	(875)				(875)
Equity settlement convertible preferred stock	87,500	$ 1	87,499
Equity settlement convertible preferred stock, shares		8,677,163
Net share settlement	(1,832)		(1,832)
Stock-based compensation	7,930		7,930
Stock-based compensation, shares		353,498
Equity settled contingent consideration	11,178		11,178
Equity settled contingent consideration, in shares		645,385
Issuance of common stock - employee stock purchase plan	847		847
Issuance of common stock - employee stock purchase plan, in shares		83,287
Equity component value of exchangeable note issuance, net	80,770		80,770
Deferred tax liability related to exchangeable note issuance	(3,499)		(3,499)
Sale of common stock warrant	50,819		50,819
Payment for bond hedge option	(70,035)		(70,035)
Ending balance, value at Sep. 30, 2019	(1,436,839)	$ 19	948,382	(27,452)	(2,442,378)	84,590
Ending balance, shares at Sep. 30, 2019		192,138,066
Beginning balance, value at Jun. 30, 2019	(1,489,289)	$ 18	855,425	(18,960)	(2,413,326)	87,554
Beginning balance, shares at Jun. 30, 2019		183,122,757
Net (loss) income	(19,777)				(19,420)	(357)
Other comprehensive income (loss)	(8,646)			(8,492)		(154)
Common stock dividends declared	(9,632)				(9,632)
Distributions to noncontrolling interest	(173)					(173)
Exchange of noncontrolling interest			2,280			(2,280)
Exchange of noncontrolling interest, shares		275,788
Equity settlement convertible preferred stock	87,500	$ 1	87,499
Equity settlement convertible preferred stock, shares		8,677,163
Net share settlement	(67)		(67)
Stock-based compensation	2,845		2,845
Stock-based compensation, shares		12,871
Issuance of common stock - employee stock purchase plan	400		400
Issuance of common stock - employee stock purchase plan, in shares		49,487
Ending balance, value at Sep. 30, 2019	$ (1,436,839)	$ 19	$ 948,382	$ (27,452)	$ (2,442,378)	$ 84,590
Ending balance, shares at Sep. 30, 2019		192,138,066