Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional paid-in capital	Accumulated other comprehensive loss	Accumulated deficit
Beginning balance (in shares) at Dec. 31, 2019		254,842,949
Beginning balance at Dec. 31, 2019	$ 334,619	$ 2,548	$ 408,667	$ (23,927)	$ (52,669)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	68,745				68,745
Other comprehensive loss	(4,477)			(4,477)
Dividends declared	(15,437)				(15,437)
Profit-sharing plan shares, net (in shares)		(385,568)
Profit‑sharing plan shares, net	(4,428)	$ (4)			(4,424)
Shares issued in connection with deferred compensation plan, net (in shares)		2,959,731
Shares issued in connection with deferred compensation plan, net	(1,830)	$ 30			(1,860)
Deferred compensation plan voluntary contributions	1,798		1,798
Payment of shareholder Put and Call rights (in shares)		(128,176)
Payment of shareholder Put and Call rights	(1,454)	$ (1)			(1,453)
Common Stock Purchase Agreement, net (in shares)		169
Common Stock Purchase Agreement, net	(57)				(57)
Stock option exercises, net (in shares)		2,184,628
Stock option exercises, net	(827)	$ 22	2,203		(3,052)
Shares issued for stock grants (in shares)		17,411
Shares issued for stock grants	219		219
Stock-based compensation expense	2,993		2,993
Shares related to restricted stock, net (in shares)		(281,789)
Shares related to restricted stock, net	(120)	$ (3)	3		(120)
Ending balance (in shares) at Jun. 30, 2020		259,209,355
Ending balance at Jun. 30, 2020	379,744	$ 2,592	415,883	(28,404)	(10,327)
Beginning balance (in shares) at Mar. 31, 2020		255,725,201
Beginning balance at Mar. 31, 2020	351,010	$ 2,556	412,038	(29,003)	(34,581)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	39,076				39,076
Other comprehensive loss	599			599
Dividends declared	(7,771)				(7,771)
Profit-sharing plan shares, net (in shares)		(198,853)
Profit‑sharing plan shares, net	(2,578)	$ (2)			(2,576)
Shares issued in connection with deferred compensation plan, net (in shares)		2,276,659
Shares issued in connection with deferred compensation plan, net	(1,529)	$ 23			(1,552)
Deferred compensation plan voluntary contributions	795		795
Payment of shareholder Put and Call rights (in shares)		(90,306)
Payment of shareholder Put and Call rights	(1,152)	$ (1)			(1,151)
Common Stock Purchase Agreement, net (in shares)		169
Common Stock Purchase Agreement, net	(57)				(57)
Stock option exercises, net (in shares)		1,486,795
Stock option exercises, net	(209)	$ 16	1,491		(1,716)
Shares issued for stock grants (in shares)		6,460
Shares issued for stock grants	100		100
Stock-based compensation expense	1,340		1,340
Shares related to restricted stock, net (in shares)		3,230
Shares related to restricted stock, net	120		119		1
Ending balance (in shares) at Jun. 30, 2020		259,209,355
Ending balance at Jun. 30, 2020	379,744	$ 2,592	415,883	(28,404)	(10,327)
Beginning balance (in shares) at Dec. 31, 2020		272,154,504
Beginning balance at Dec. 31, 2020	341,599	$ 2,722	741,113	(26,233)	(376,003)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	101,916				101,916
Other comprehensive loss	(28,653)			(28,653)
Purchase of capped call options, net of tax of $6,334	(39,021)		(39,021)
Dividends declared	(16,591)				(16,591)
Shares issued in connection with deferred compensation plan, net (in shares)		2,202,079
Shares issued in connection with deferred compensation plan, net	(61,912)	$ 22			(61,934)
Deferred compensation plan voluntary contributions	1,493		1,493
Shares issued in connection with Executive Bonus Plan, net (in shares)		149,447
Shares issued in connection with Executive Bonus Plan, net	7,007	$ 2	11,721		(4,716)
Stock option exercises, net (in shares)		3,657,058
Stock option exercises, net	(24,703)	$ 36	4,288		(29,027)
Shares issued for stock grants (in shares)		7,824
Shares issued for stock grants	450		450
Stock-based compensation expense	8,548		8,548
Shares related to restricted stock, net (in shares)		(123,127)
Shares related to restricted stock, net	(709)	$ (1)			(708)
Ending balance (in shares) at Jun. 30, 2021		281,189,127
Ending balance at Jun. 30, 2021	471,814	$ 2,812	910,951	(54,886)	(387,063)
Beginning balance (in shares) at Mar. 31, 2021		273,722,483
Beginning balance at Mar. 31, 2021	353,997	$ 2,737	732,635	(35,394)	(345,981)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	44,910				44,910
Other comprehensive loss	(19,492)			(19,492)
Shares issued related to acquisition (in shares)		3,141,342
Shares issued related to acquisition	182,390	$ 31	182,359
Purchase of capped call options, net of tax of $6,334	(19,591)		(19,591)
Dividends declared	(8,372)				(8,372)
Shares issued in connection with deferred compensation plan, net (in shares)		1,862,576
Shares issued in connection with deferred compensation plan, net	(53,053)	$ 19			(53,072)
Deferred compensation plan voluntary contributions	639		639
Shares issued in connection with Executive Bonus Plan, net (in shares)		69,486
Shares issued in connection with Executive Bonus Plan, net	3,470	$ 1	6,148		(2,679)
Stock option exercises, net (in shares)		2,393,937
Stock option exercises, net	(19,296)	$ 24	2,549		(21,869)
Shares issued for stock grants (in shares)		7,824
Shares issued for stock grants	450		450
Stock-based compensation expense	5,762		5,762
Shares related to restricted stock, net (in shares)		(8,521)
Shares related to restricted stock, net	0	$ 0			0
Ending balance (in shares) at Jun. 30, 2021		281,189,127
Ending balance at Jun. 30, 2021	$ 471,814	$ 2,812	$ 910,951	$ (54,886)	$ (387,063)