Annual report pursuant to Section 13 and 15(d)

Basis of Presentation and Summary of Significant Accounting Policies - Calculation of Earnings per Share (Details)

v3.8.0.1
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, 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
Organization, Consolidation and Presentation of Financial Statements [Abstract]                      
Weighted-average shares outstanding - basic (shares) 21,109 21,071 21,013 20,938 20,898 20,887 20,832 20,708 21,032 20,831 19,790
Dilutive potential common shares:                      
Restricted stock (shares)                 141 0 56
Stock options (shares)                 1,000 0 882
Warrants (shares)                 94 0 0
2019 Convertible Senior Notes (shares)                 1,214 0 499
Shares used to compute diluted income per share (shares) 21,109 23,551 23,216 23,019 20,898 22,997 20,832 22,284 23,481 20,831 21,228
Potentially dilutive shares excluded from calculation due to anti-dilutive effect (shares)                 335 3,544 3,333