Earnings Per Share - Computation of Basic and Diluted Earnings Per Share for Continuing Operations (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Income (loss) from continuing operations	$ (90)	$ 20,096	$ 21,479	$ 36,862	$ (1,136)	$ 18,006	$ 16,614	$ 37,565	$ 78,347	$ 71,049	$ 61,573
Basic
Weighted average common shares outstanding	54,039	54,403	54,142	54,571	54,547	54,268	54,090	54,287	54,288	54,299	54,561
Diluted
Stock options (in shares)									802	1,288	1,542
Restricted stock awards (in shares)									195	234	302
Contingent shares									74	74	82
Diluted weighted average common shares outstanding (3)	54,039	55,360	55,116	55,945	54,547	55,816	55,495	55,915	55,359	55,895	56,487
Earnings Per Share:
Basic earnings per share from continuing operations (in dollars per share)	$ 0	$ 0.37	$ 0.40	$ 0.68	$ (0.02)	$ 0.33	$ 0.31	$ 0.69	$ 1.44	$ 1.31	$ 1.13
Diluted earnings per share from continuing operations (in dollars per share)	$ 0	$ 0.36	$ 0.39	$ 0.66	$ (0.02)	$ 0.32	$ 0.30	$ 0.67	$ 1.42	$ 1.27	$ 1.09
Share-based Payment Arrangement
Dilutive Securities Included And Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Share based awards excluded from the calculation of diluted earnings per share (in shares)									300	500	400
Performance Shares
Dilutive Securities Included And Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Share based awards excluded from the calculation of diluted earnings per share (in shares)									300	200