(Loss) Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Long-term Debt, Excluding Current Maturities	$ 949,775		$ 949,775		$ 502,539
Earnings Per Share, Basic [Abstract]
Net (loss) income attributable to controlling interests and available to common shareholders	(175,561)	$ 27,490	(161,304)	$ 63,022
Less: Undistributed earnings allocated to unvested RSAs		(9)		(34)
Net (loss) income available to common shareholders	(175,561)	27,481	(161,304)	62,988
Earnings Per Share, Diluted [Abstract]
Add: Undistributed earnings allocated to restricted shares, Diluted		9		34
Less: Undistributed earnings reallocated to RSAs		(9)		(33)
Net (loss) income available to common shareholders and assumed conversions	$ (175,561)	$ 27,481	$ (161,304)	$ 62,989
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Weighted Average Shares Outstanding, Basic	45,662,543	45,252,869	45,597,558	45,175,604
Stock options added to the denominator under the treasury stock method		20,557		29,451
RSUs added to the denominator under the treasury stock method		576,635		560,180
Weighted Average Shares Outstanding, Diluted	45,662,543	45,850,061	45,597,558	45,765,235
Net (loss) income per common share – basic	$ (3.84)	$ 0.61	$ (3.54)	$ 1.39
Net (loss) income per common share – diluted	$ (3.84)	$ 0.60	$ (3.54)	$ 1.38
Restricted Stock Awards [Member]
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Antidilutive shares excluded from computation of diluted earnings per share		7,217		12,920
Convertible Senior Notes 1.00 percent due 2020
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Long-term Debt, Excluding Current Maturities	$ 249,189		$ 249,189		$ 241,068
Debt Instrument, Interest Rate, Stated Percentage	1.00%		1.00%		1.00%