Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock Class A	Common Stock Class B	Treasury Stock Class A	Treasury Stock Class B	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Cumulative Effect, Period of Adoption, Adjustment Revision of Prior Period, Adjustment	Retained (Deficit) Earnings	Retained (Deficit) Earnings Cumulative Effect, Period of Adoption, Adjustment Revision of Prior Period, Adjustment
Balance at beginning of period at Dec. 31, 2018	$ 455,548	$ 153	$ 553	$ (8,045)	$ (21,719)	$ 604,401	$ (86)		$ (119,709)
Balance at beginning of period (in shares) at Dec. 31, 2018		15,281	55,284	(856)	(2,147)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock	13					13
Share conversion - Class B to A		$ 4	$ (4)
Repurchase of shares	(1,344)			$ (1,344)
Shares withheld related to net settlement of equity awards	(318)				$ (318)
Exercise of options	221		1			220
Other comprehensive income/(loss)	12						12
Share-based compensation	1,547					1,547
Dividends paid	(41)								(41)
Net income	14,527								14,527
Balance at end of period at Mar. 31, 2019	470,165	$ 157	$ 550	$ (9,389)	$ (22,037)	606,181	(12)		(105,285)
Balance at end of period (in shares) at Mar. 31, 2019		15,664	55,014	(979)	(2,176)
Balance at beginning of period at Dec. 31, 2018	455,548	$ 153	$ 553	$ (8,045)	$ (21,719)	604,401	(86)		(119,709)
Balance at beginning of period (in shares) at Dec. 31, 2018		15,281	55,284	(856)	(2,147)
Increase (Decrease) in Stockholders' Equity
Other comprehensive income/(loss)	4						4
Net income	28,910
Balance at end of period at Jun. 30, 2019	486,951	$ 165	$ 544	$ (11,337)	$ (22,160)	610,685	(20)		(90,926)
Balance at end of period (in shares) at Jun. 30, 2019		16,474	54,359	(1,092)	(2,184)
Increase (Decrease) in Stockholders' Equity
Cumulative effect of adoption of ASU 2016-01 and 2018-02								$ 62		$ (62)
Balance at beginning of period at Mar. 31, 2019	470,165	$ 157	$ 550	$ (9,389)	$ (22,037)	606,181	(12)		(105,285)
Balance at beginning of period (in shares) at Mar. 31, 2019		15,664	55,014	(979)	(2,176)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock	16					16
Share conversion - Class B to A		$ 8	$ (8)
Repurchase of shares	(1,948)			$ (1,948)
Shares withheld related to net settlement of equity awards	(123)				$ (123)
Exercise of options	735		2			733
Other comprehensive income/(loss)	(8)						(8)
Share-based compensation	3,755					3,755
Dividends paid	(24)								(24)
Net income	14,383								14,383
Balance at end of period at Jun. 30, 2019	486,951	$ 165	$ 544	$ (11,337)	$ (22,160)	610,685	(20)		(90,926)
Balance at end of period (in shares) at Jun. 30, 2019		16,474	54,359	(1,092)	(2,184)
Increase (Decrease) in Stockholders' Equity
Cumulative effect of adoption of ASU 2016-01 and 2018-02								$ 62
Cumulative effect of adoption of ASU 2016-01 and 2018-02	(34,705)
Balance at beginning of period at Dec. 31, 2019	537,871	$ 181	$ 539	$ (21,524)	$ (31,386)	624,766			(34,705)
Balance at beginning of period (in shares) at Dec. 31, 2019		18,100	53,937	(1,685)	(2,656)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock	26					26
Share conversion - Class B to A		$ 4	$ (4)
Repurchase of shares	(4,394)			$ (4,394)
Shares withheld related to net settlement of equity awards	(8,787)				$ (8,787)
Vesting of restricted share grants			7			(7)
Exercise of options	1,693		3			1,690
Other comprehensive income/(loss)	(4,887)						(4,887)
Share-based compensation	5,993					5,993
Dividends paid	(3,601)								(3,601)
Net income	57,166								57,166
Balance at end of period at Mar. 31, 2020	581,080	$ 185	$ 545	$ (25,918)	$ (40,173)	632,468	(4,887)		18,860
Balance at end of period (in shares) at Mar. 31, 2020		18,508	54,538	(1,925)	(3,101)
Balance at beginning of period at Dec. 31, 2019	537,871	$ 181	$ 539	$ (21,524)	$ (31,386)	624,766			(34,705)
Balance at beginning of period (in shares) at Dec. 31, 2019		18,100	53,937	(1,685)	(2,656)
Increase (Decrease) in Stockholders' Equity
Other comprehensive income/(loss)	(8,403)						(8,403)
Net income	101,886
Balance at end of period at Jun. 30, 2020	614,840	$ 187	$ 545	$ (33,104)	$ (40,912)	636,386	(8,403)		60,141
Balance at end of period (in shares) at Jun. 30, 2020		18,717	54,504	(2,382)	(3,144)
Balance at beginning of period at Mar. 31, 2020	581,080	$ 185	$ 545	$ (25,918)	$ (40,173)	632,468	(4,887)		18,860
Balance at beginning of period (in shares) at Mar. 31, 2020		18,508	54,538	(1,925)	(3,101)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock	32					32
Share conversion - Class B to A		$ 2	$ (2)
Repurchase of shares	(7,186)			$ (7,186)
Shares withheld related to net settlement of equity awards	(739)				$ (739)
Vesting of restricted share grants			2			(2)
Exercise of options	1					1
Other comprehensive income/(loss)	(3,516)						(3,516)
Share-based compensation	3,887					3,887
Dividends paid	(3,439)								(3,439)
Net income	44,720								44,720
Balance at end of period at Jun. 30, 2020	614,840	$ 187	$ 545	$ (33,104)	$ (40,912)	$ 636,386	$ (8,403)		$ 60,141
Balance at end of period (in shares) at Jun. 30, 2020		18,717	54,504	(2,382)	(3,144)
Increase (Decrease) in Stockholders' Equity
Cumulative effect of adoption of ASU 2016-01 and 2018-02	$ 60,141