Earnings Per Share ("EPS") (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator
Net income									$ 68,972	$ 161,673	$ 554,839
Net income attributable to noncontrolling interests									(8,952)	(15,543)	(37,844)
Net income attributable to the Company	$ 11,749	$ 74,028	$ 7,816	$ (33,573)	$ 32,751	$ 17,498	$ 26,638	$ 69,243	60,020	146,130	516,995
Allocation of earnings to participating securities									(1,106)	(757)	(779)
Numerator for basic and diluted EPS—net income attributable to common stockholders									$ 58,914	$ 145,373	$ 516,216
Denominator
Denominator for basic EPS—weighted average number of common shares outstanding (shares)									141,142,000	141,877,000	146,599,000
Effect of dilutive securities
Share and unit based compensation (shares)									2,000	36,000	112,000
Denominator for diluted EPS—weighted average number of common shares outstanding (shares)									141,144,000	141,913,000	146,711,000
EPS—net income attributable to common stockholders:
Basic (dollars per share)	$ 0.08	$ 0.52	$ 0.05	$ (0.24)	$ 0.23	$ 0.12	$ 0.19	$ 0.48	$ 0.42	$ 1.02	$ 3.52
Diluted (dollars per share)	$ 0.08	$ 0.52	$ 0.05	$ (0.24)	$ 0.23	$ 0.12	$ 0.19	$ 0.48	$ 0.42	$ 1.02	$ 3.52
Convertible preferred units
Antidilutive securities
Antidilutive securities (shares)									90,619	90,619	133,366
Partnership unit
Antidilutive securities
Antidilutive securities (shares)									10,360,390	10,416,321	10,721,271