Consolidated Statements Of Changes In Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total		Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income
Beginning Balance (in shares) at Dec. 31, 2014			35,557
Beginning Balance at Dec. 31, 2014	$ 1,370,765		$ 356	$ 736,294	$ 635,017	$ (902)
Shares issued under employee benefit programs, Shares			428
Excess tax benefit (shortfall) from sharebased payments	(572)			(572)
Stock-based compensation expense	10,464			10,464
Shares issued under employee benefit programs	1,859		$ 4	1,855
Net Income (loss)	66,821	[1]			66,821
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(3,174)					(3,174)
Ending Balance (in shares) at Dec. 31, 2015			35,985
Ending Balance at Dec. 31, 2015	1,446,163		$ 360	748,041	701,838	(4,076)
Shares issued under employee benefit programs, Shares			482
Excess tax benefit (shortfall) from sharebased payments	(1,863)			(1,863)
Stock-based compensation expense	7,372			7,372
Shares issued under employee benefit programs	849		$ 5	844
Net Income (loss)	(63,846)				(63,846)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	14,321					14,321
Ending Balance (in shares) at Dec. 31, 2016			36,467
Ending Balance at Dec. 31, 2016	1,402,996		$ 365	754,394	637,992	10,245
Shares issued under employee benefit programs, Shares			677
Excess tax benefit (shortfall) from sharebased payments	3,185			0
Stock-based compensation expense	5,981			5,981
Shares issued under employee benefit programs	(91)		$ 6	(97)
Net Income (loss)	27,421				27,421
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(1,568)					(1,568)
Ending Balance (in shares) at Dec. 31, 2017			37,144
Ending Balance at Dec. 31, 2017	1,437,924		$ 371	$ 760,278	668,598	$ 8,677
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 3,200				$ 3,185

[1] The Company's net income for 2017 was favorably impacted by U.S. tax reform legislation that was enacted in December 2017. As a result of tax reform, the Company recorded a benefit of $125,225 related to the repricing of its deferred tax liabilities. Such benefits were reduced primarily by tax expense related to credits that may not be utilized prior to their expiration. Excluding these one-time tax items from the Company's December 31, 2017 results, its net loss would have been $(82,687) or $(2.24) per diluted share for the year ended December 31, 2017. See Note 9 for further information.