Basis of Presentation and Summary of Significant Accounting Policies - Calculation of Earnings per Share (Details) - shares shares in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Weighted-average common shares outstanding - basic (shares)	17,243	18,770	19,558	20,447	21,071	21,148	21,212	21,209	18,995	21,160	21,032
Dilutive potential common shares:
Restricted stock (shares)									43	72	141
Stock options (shares)									719	1,125	1,000
Warrants (shares)									0	1,017	94
2019 Convertible Senior Notes (shares)									0	693	1,214
Shares used to compute diluted income per share (shares)	17,243	18,770	19,558	21,277	21,071	24,052	24,438	24,800	19,757	24,067	23,481
Potentially dilutive shares excluded from calculation due to anti-dilutive effect (shares)									8,926	2,845	335