Changes in Equity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Balance at the beginning of the period	$ 1,787,889	$ 1,704,780
Cumulative effect of accounting change		(5,447)
Net income (loss)	4,722	(10,942)
Other comprehensive income (loss)	1,351	(878)
Share-based compensation	4,783	5,399
Issuance of common stock, net	(2,364)	(2,308)
Contributions from noncontrolling interests	2,798
Distributions to noncontrolling interests	(4,000)	(5,000)
Balance at the end of the period	1,795,179	1,685,604
Common Stock [Member]
Balance at the beginning of the period	50,026	49,781
Issuance of common stock, net	154	132
Balance at the end of the period	50,180	49,913
Additional Paid-in Capital [Member]
Balance at the beginning of the period	1,102,919	1,084,205
Share-based compensation	4,783	5,399
Issuance of common stock, net	(2,518)	(2,440)
Balance at the end of the period	1,105,184	1,087,164
Retained Earnings [Member]
Balance at the beginning of the period	701,681	622,007
Cumulative effect of accounting change		(3,684)
Net income (loss)	(356)	(12,124)
Balance at the end of the period	701,325	606,199
Accumulated Other Comprehensive Loss [Member]
Balance at the beginning of the period	(45,449)	(42,718)
Other comprehensive income (loss)	1,249	(878)
Balance at the end of the period	(44,200)	(43,596)
Noncontrolling Interests [Member]
Balance at the beginning of the period	(21,288)	(8,495)
Cumulative effect of accounting change		(1,763)
Net income (loss)	5,078	1,182
Other comprehensive income (loss)	102
Contributions from noncontrolling interests	2,798
Distributions to noncontrolling interests	(4,000)	(5,000)
Balance at the end of the period	$ (17,310)	$ (14,076)