Condensed Consolidated Statements of Stockholders' Equity Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other comprehensive (Loss) Income [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, shares, outstanding		109,910
Total stockholders' equity	$ 286,517	$ 1,099	$ 838,436	$ 805,924	$ (1,347,677)	$ (11,265)
ASU adoption adjustment	(1,976)			(1,976)
Net earnings	7,323			7,323
Total other comprehensive income (loss)	521					521
Exercise of stock options, shares		284
Exercise of stock options	2,892	$ 3	2,889
Vesting of restricted share units, shares		218
Vesting of restricted share units	0	$ 2	(2)
Tax effect of stock awards vested and options exercised	(1,734)		(1,734)
Stock-based compensation	709		709
Net earnings	133,055			133,055
Total other comprehensive income (loss)	(40)
Common stock, shares, outstanding		110,412
Total stockholders' equity	294,252	$ 1,104	840,298	811,271	(1,347,677)	(10,744)
Net earnings	94,455			94,455
Total other comprehensive income (loss)	(217)					(217)
Exercise of stock options, shares		101
Exercise of stock options	1,418	$ 1	1,417
Vesting of restricted share units, shares		49
Vesting of restricted share units	0
Stock-based compensation	1,982		1,982
Common stock, shares, outstanding		110,562
Total stockholders' equity	391,890	$ 1,105	843,697	905,726	(1,347,677)	(10,961)
Net earnings	31,277			31,277
Total other comprehensive income (loss)	(344)					(344)
Exercise of stock options, shares		105
Exercise of stock options	1,503	$ 1	1,502
Stock-based compensation	1,952		1,952
Dividends declared	(13,707)			(13,707)
MP Acquisition, shares		439
MP Acquisition	19,169	$ 4	19,165
Common stock, shares, outstanding		111,106
Total stockholders' equity	431,740	$ 1,110	866,316	923,296	(1,347,677)	(11,305)
Common stock, shares, outstanding		111,166
Total stockholders' equity	458,963	$ 1,110	869,617	947,875	(1,348,969)	(10,670)
ASU adoption adjustment	(769)			(769)
Net earnings	49,292			49,292
Total other comprehensive income (loss)	(3,906)					(3,906)
Purchase of treasury stock	(26,525)	$ (14)			(26,511)
Exercise of stock options, shares		69
Exercise of stock options	1,195	$ 1	1,194
Vesting of restricted share units, shares		434
Vesting of restricted share units	0	$ 4	(4)
Tax effect of stock awards vested and options exercised	(5,270)		(5,270)
Stock-based compensation	3,043		3,043
Net earnings	151,815			151,815
Total other comprehensive income (loss)	(3,280)
Purchase of treasury stock	(26,600)
Common stock, shares, outstanding		111,669
Total stockholders' equity	476,023	$ 1,101	868,580	996,398	(1,375,480)	(14,576)
Net earnings	38,493			38,493
Total other comprehensive income (loss)	17					17
Exercise of stock options, shares		42
Exercise of stock options	486		486
Stock-based compensation	2,849		2,849
Dividends declared	(31,292)			(31,292)
Common stock, shares, outstanding		111,711
Total stockholders' equity	486,576	$ 1,101	871,915	1,003,599	(1,375,480)	(14,559)
Net earnings	64,030			64,030
Total other comprehensive income (loss)	609
Purchase of treasury stock	(61)	$ 0			(61)
Exercise of stock options, shares		226
Exercise of stock options	4,055	$ 2	4,053
Vesting of restricted share units, shares		87
Vesting of restricted share units	0	$ 0	0
Stock-based compensation	2,997		2,997
Dividends declared	(15,869)			(15,869)
Common stock, shares, outstanding		112,024
Total stockholders' equity	$ 542,337	$ 1,103	$ 878,965	$ 1,051,760	$ (1,375,541)	$ (13,950)