Earnings (Loss) per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic:
Net (loss) income attributable to controlling interests and available to common shareholders	$ 15,954	$ (175,561)	$ 15,158	$ (901)	$ 24,969	$ 27,490	$ 20,148	$ 15,384	$ (145,350)	$ 87,991	$ 67,080
Less: Undistributed earnings allocated to unvested RSAs										(42)	(94)
Net (loss) income available to common shareholders									(145,350)	87,949	66,986
Diluted:
Add: Undistributed earnings allocated to restricted shares, Diluted										42	94
Less: Undistributed earnings reallocated to RSAs										(41)	(93)
Net (loss) income available to common shareholders and assumed conversions									$ (145,350)	$ 87,950	$ 66,987
Weighted Average Shares Outstanding
Weighted Average Shares Outstanding, Basic									45,619,679	45,206,119	44,796,701
Stock options added to the denominator under the treasury stock method										24,509	63,657
RSUs added to the denominator under the treasury stock method										590,899	508,329
Weighted Average Shares Outstanding, Diluted									45,619,679	45,821,527	45,368,687
Net (loss) income per common share – basic	$ 0.34	$ (3.84)	$ 0.33	$ (0.02)	$ 0.55	$ 0.61	$ 0.45	$ 0.34	$ (3.19)	$ 1.95	$ 1.50
Net (loss) income per common share – diluted	$ 0.34	$ (3.84)	$ 0.33	$ (0.02)	$ 0.54	$ 0.60	$ 0.44	$ 0.34	$ (3.19)	$ 1.92	$ 1.48
Antidilutive shares excluded from computation of diluted earnings per share									2,821	12,316	31,005