Consolidated Statement of Shareholders' Equity Statement - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]
Beginning Balance, Shares		27,788,000
Beginning balance	$ 535,322	$ 278	$ 172,771	$ 367,021	$ (4,748)
Issuance of common stock under employee stock plans (in shares)		125,000
Stock Issued During Period, Value, Stock Options Exercised	4,981	$ 1	4,980
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures (in shares)		391,000
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	0	$ 4	(4)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	18,742		18,742
Shares Paid for Tax Withholding for Share Based Compensation (in shares)		(59,000)
Stock Withheld to Cover Tax Withholding Requirements Upon Vesting to Restricted Stock Units Amount	(7,277)	$ (1)	(7,276)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	5,803		5,803
Adjustments to Additional Paid in Capital Directors Deferred Compensation	55		55
Net income	65,259			65,259
Beginning Balance, Shares		28,123,000
Beginning balance	$ 579,576	$ 281	184,663	396,748	(2,116)
Issuance of common stock under employee stock plans (in shares)	301,000	9,000
Stock Issued During Period, Value, Stock Options Exercised		$ 0	301
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures (in shares)		113,000
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	$ 0	$ 1	(1)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	4,284		4,284
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	3,171
Adjustments to Additional Paid in Capital Directors Deferred Compensation	21		21
Net income	35,532			35,532
Beginning Balance, Shares		28,245,000
Beginning balance	$ 622,885	$ 282	189,268	432,280	1,055
Beginning Balance, Shares	28,352,000	28,352,000
Beginning balance	$ 652,069	$ 284	196,455	452,321	3,009
Issuance of common stock under employee stock plans (in shares)		122,000
Stock Issued During Period, Value, Stock Options Exercised	4,048	$ 1	4,047
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures (in shares)		356,000
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	0	$ 3	(3)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	20,904		20,904
Shares Paid for Tax Withholding for Share Based Compensation (in shares)		(46,000)
Stock Withheld to Cover Tax Withholding Requirements Upon Vesting to Restricted Stock Units Amount	(1,845)		(1,845)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(2,058)				(2,058)
Adjustments to Additional Paid in Capital Directors Deferred Compensation	63		63
Net income	$ 133,733			133,733
Stock Repurchased and Retired During Period, Shares	(664,000)
Stock Repurchased and Retired During Period, Value	$ (25,000)	$ (7)	(24,993)
Beginning Balance, Shares		27,998,000
Beginning balance	682,062	$ 280	184,436	492,802	4,544
Issuance of common stock under employee stock plans (in shares)		10,000
Stock Issued During Period, Value, Stock Options Exercised	358	$ 0	358
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures (in shares)		113,000
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	0	$ 1	(1)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	9,843		9,843
Shares Paid for Tax Withholding for Share Based Compensation (in shares)		(1,000)
Stock Withheld to Cover Tax Withholding Requirements Upon Vesting to Restricted Stock Units Amount	(29)	$ 0	(29)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(3,593)				(3,593)
Adjustments to Additional Paid in Capital Directors Deferred Compensation	21		21
Net income	$ 93,252			93,252
Beginning Balance, Shares	28,120,000	28,120,000
Beginning balance	$ 781,914	$ 281	$ 194,628	$ 586,054	$ 951