Condensed Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data	Total	Common Stock	Additional Paid-In Capital	Accumulated Earnings	Accumulated Other Comprehensive Loss
Balance at Dec. 31, 2012	$ 405,816	$ 232	$ 88,029	$ 319,329	$ (1,774)
Balance, Shares at Dec. 31, 2012	23,191,000	23,191,000
Net income	30,460			30,460
Unrealized loss on derivative instruments, net of tax	(954)				(954)
Unrealized loss on foreign currency translation adjustments, net of tax	(697)				(697)
Exercise of stock options and issuance of share-based awards, net of shares withheld for employee taxes, Shares		413,000
Exercise of stock options and issuance of share-based awards, net of shares withheld for employee taxes	(6,061)	4	(6,065)
Repurchase of common stock, Shares		(24,000)
Repurchase of common stock	(729)		(729)
Issuance of common stock, Shares		1,672,000
Issuance of common stock	62,352	17	62,335
Stock-based compensation	5,180		5,180
Issuance of convertible notes	26,850		26,850
Purchase of convertible hedge	(15,750)		(15,750)
Tax benefit related to stock-based compensation	3,749		3,749
Tax benefit related to convertible notes, net	154		154
Balance at Jun. 30, 2013	$ 510,370	$ 253	$ 163,753	$ 349,789	$ (3,425)
Balance, Shares at Jun. 30, 2013	25,252,000	25,252,000