CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]	Total
Balance at Dec. 31, 2015	$ 49,073	$ 1,035,516	$ 377,803	$ (42,165)		$ 1,420,227
Net income			95,822			95,822
Other comprehensive income (loss)				(3,248)		(3,248)
Tax effect of share-based compensation		(457)				(457)
Share-based compensation		13,423				13,423
Issuance of common stock, net	138	676				814
Convertible note proceeds allocated to conversion option, net		26,442				26,442
Balance at Dec. 31, 2016	49,211	1,075,600	473,625	(45,413)		1,553,023
Net income			148,382		$ 6,162	154,544
Other comprehensive income (loss)				2,695		2,695
Share-based compensation		20,877				20,877
Issuance of common stock, net	570	(12,272)				(11,702)
Contributions from noncontrolling interests					2,842	2,842
Distributions to noncontrolling interests					(17,499)	(17,499)
Balance at Dec. 31, 2017	49,781	1,084,205	622,007	(42,718)	(8,495)	1,704,780
Net income			83,436		14,345	97,781
Other comprehensive income (loss)				(2,731)	(221)	(2,952)
Share-based compensation		21,544				21,544
Issuance of common stock, net	245	(2,830)				(2,585)
Contributions from noncontrolling interests					3,797	3,797
Distributions to noncontrolling interests					(29,000)	(29,000)
Balance at Dec. 31, 2018	$ 50,026	$ 1,102,919	701,681	$ (45,449)	(21,288)	1,787,889
Cumulative effect of accounting change			$ (3,762)		$ (1,714)	$ (5,476)