Condensed Consolidated Statements of Redeemable Preferred Stock and Shareholders' Equity - USD ($) $ in Thousands	Total	Redeemable Preferred Stock	Common Stock	Paid in Capital in Excess of Par	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balances, beginning of period (in shares) at Dec. 31, 2017		2,500,000	6,419,000
Balances, beginning of period at Dec. 31, 2017	$ 258,910	$ 49,471	$ 64	$ 2,319	$ 256,301	$ 226
Net income	25,117				25,117
Net unrealized (loss) gain from currency translation adjustment, net of tax benefit (expense)	(590)					(590)
Net unrealized (loss) gain from derivative instruments, net of tax benefit (expense)	1,267					1,267
Shares repurchased (in shares)			(425,000)
Shares repurchased	(14,567)		$ (4)	(5,361)	(9,202)
Shares issued under stock compensation plans (in shares)			278,000
Shares issued under stock compensation plans	292		$ 2	290
Cancellation of restricted stock in satisfaction of withholding tax (in shares)			(42,000)
Cancellation of restricted stock in satisfaction of withholding tax	(1,252)		$ 0	(1,252)
Stock-based compensation expense	4,004			4,004
Accretion of preferred shares issuance costs	(62)	$ 62			(62)
Preferred stock dividends	(2,431)				(2,431)
Balances, end of period (in shares) at Sep. 30, 2018		2,500,000	6,230,000
Balances, end of period at Sep. 30, 2018	270,688	$ 49,533	$ 62	0	269,664	962
Balances, beginning of period (in shares) at Jun. 30, 2018		2,500,000	6,365,000
Balances, beginning of period at Jun. 30, 2018	265,287	$ 49,512	$ 64	1,474	262,548	1,201
Net income	9,674				9,674
Net unrealized (loss) gain from currency translation adjustment, net of tax benefit (expense)	(411)					(411)
Net unrealized (loss) gain from derivative instruments, net of tax benefit (expense)	172					172
Shares repurchased (in shares)			(128,000)
Shares repurchased	(4,383)		$ (1)	(2,664)	(1,718)
Shares issued under stock compensation plans (in shares)			6,000
Shares issued under stock compensation plans	174		$ (1)	175
Cancellation of restricted stock in satisfaction of withholding tax (in shares)			(13,000)
Cancellation of restricted stock in satisfaction of withholding tax	(404)			(404)
Stock-based compensation expense	1,419			1,419
Accretion of preferred shares issuance costs	(21)	$ 21			(21)
Preferred stock dividends	(819)				(819)
Balances, end of period (in shares) at Sep. 30, 2018		2,500,000	6,230,000
Balances, end of period at Sep. 30, 2018	270,688	$ 49,533	$ 62	0	269,664	962
Balances, beginning of period (in shares) at Dec. 31, 2018		2,500,000	6,176,000
Balances, beginning of period at Dec. 31, 2018	286,787	$ 49,554	$ 62	0	286,623	102
Net income	61,926				61,926
Net unrealized (loss) gain from currency translation adjustment, net of tax benefit (expense)	(378)					(378)
Net unrealized (loss) gain from derivative instruments, net of tax benefit (expense)	(1,477)					(1,477)
Shares repurchased (in shares)			(72,324)
Shares repurchased	(3,567)		$ (1)	(2,087)	(1,479)
Shares issued under stock compensation plans (in shares)			290,000
Shares issued under stock compensation plans	335		$ 3	332
Cancellation of restricted stock in satisfaction of withholding tax (in shares)			(37,000)
Cancellation of restricted stock in satisfaction of withholding tax	(1,460)			(1,460)
Stock-based compensation expense	5,588			5,588
Accretion of preferred shares issuance costs	(63)	$ 63			(63)
Preferred stock dividends	(2,431)				(2,431)
Balances, end of period (in shares) at Sep. 30, 2019		2,500,000	6,357,000
Balances, end of period at Sep. 30, 2019	345,493	$ 49,617	$ 64	2,373	344,809	(1,753)
Balances, beginning of period (in shares) at Jun. 30, 2019		2,500,000	6,350,000
Balances, beginning of period at Jun. 30, 2019	320,413	$ 49,596	$ 64	0	321,577	(1,228)
Net income	24,073				24,073
Net unrealized (loss) gain from currency translation adjustment, net of tax benefit (expense)	(352)					(352)
Net unrealized (loss) gain from derivative instruments, net of tax benefit (expense)	(173)					(173)
Shares issued under stock compensation plans (in shares)			7,000
Shares issued under stock compensation plans	172		$ 0	172
Stock-based compensation expense	2,201			2,201
Accretion of preferred shares issuance costs	(21)	$ 21			(21)
Preferred stock dividends	(820)				(820)
Balances, end of period (in shares) at Sep. 30, 2019		2,500,000	6,357,000
Balances, end of period at Sep. 30, 2019	$ 345,493	$ 49,617	$ 64	$ 2,373	$ 344,809	$ (1,753)