Consolidated Statement of Changes in Stockholders' Equity - 9 months ended Sep. 30, 2018 - USD ($) $ in Thousands	Total	Common Stock Voting [Member]	Additional Paid-in Capital [Member]	Treasury Stock - Common Stock Voting [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning Balance at Dec. 31, 2017	$ 514,768	$ 121	$ 331,081	$ (159,791)	$ 353,583	$ (10,226)
Net income	127,021				127,021
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	(1,602)					(1,602)
Unrealized net (loss) on securities available-for-sale, net of tax	(205)					(205)
Stock-based compensation	11,551		11,551
Exercise of stock options	1,387		1,387
Withholding tax payments on restricted stock vesting and stock option exercises	(7,940)		(7,940)
Repurchases of common stock	(18,985)			(18,985)
Cash dividend on common stock	(47,377)				(47,377)
Ending Balance at Sep. 30, 2018	$ 578,618	$ 121	$ 336,079	$ (178,776)	$ 433,227	$ (12,033)

Adjustments related to tax withholding (expense) benefit for share based compensation.

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Amount of increase to additional paid-in capital (APIC) from recognition of equity-based compensation.

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Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.

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Value of stock issued as a result of the exercise of stock options.

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