Earnings 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	Jun. 06, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock Repurchased During Period, Shares												380,637
shares repurchased from related party, price paid												$ 8,500
purchase price per shares, repurchased shares												$ 22.42
Earnings Per Share Reconciliation [Abstract]
Earnings from continuing operations	$ 94,091	$ (28,229)	$ (53,918)	$ 9,796	$ (755)	$ 2,116	$ 11,528	$ 8,171	$ 21,740	$ 21,060	$ 39,155
Weighted-average shares outstanding for basic earnings per share (in shares)	58,733,000	58,733,000	59,035,000	59,133,000	59,083,000	59,379,000	63,267,000	63,636,000	58,907,000	61,330,000	64,242,000
Restricted stock (in shares)									241,000	327,700	348,600
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	8,100,000								8,100,000
Common equivalent shares:
Effect of stock-based compensation awards (in shares)									779,000	1,664,000	885,000
Weighted-average shares outstanding assuming dilution (in shares)	68,987,000	58,733,000	59,035,000	64,949,000	59,083,000	60,283,000	66,763,000	65,057,000	59,686,000	62,994,000	65,127,000
Basic earnings per share from continuing operations (in dollars per share)	$ 1.60	$ (0.48)	$ (0.91)	$ 0.17	$ (0.01)	$ 0.04	$ 0.18	$ 0.13	$ 0.37	$ 0.34	$ 0.61
Diluted earnings per share from continuing operations (in dollars per share)	$ 1.11	$ (0.48)	$ (0.91)	$ 0.13	$ (0.01)	$ 0.04	$ 0.12	$ 0.13	$ 0.36	$ 0.33	$ 0.60
Amazon Warrant [Member]
Earnings Per Share Reconciliation [Abstract]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	14,830,000				11,060,000				14,830,000	11,060,000