Consolidated Statement Of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Equity
Cumulative effect of adoption of ASU | ASU 2016-01 [Member]	$ 0			$ (348)		$ 348
Cumulative effect of adoption of ASU | ASU 2014-09 [Member]	163			163
Balance at Jun. 30, 2018	$ 1,737,049	$ 1,084	$ 1,148,196	878,516	$ (106,507)	(184,240)
Balance, shares at Jun. 30, 2018	108,422	108,422			4,470
Increase (Decrease) in Stockholders' Equity
Net income	$ (103,926)			(103,926)
Other comprehensive loss	(41,467)					(41,467)
Issuance of common stock pursuant to stock-based compensation plans	0	$ 3	(3)
Issuance of common stock pursuant to stock-based compensation plans, shares		269
Shares withheld for payment of employee payroll taxes due on shares issued under stock-based compensation plans	(2,922)				$ (2,922)
Shares withheld for payment of employee payroll taxes due on shares issued under stock based compensation plans, shares					114
Stock-based compensation expense	2,046		2,046
Balance at Dec. 31, 2018	$ 1,590,943	$ 1,087	$ 1,150,239	$ 774,405	$ (109,429)	$ (225,359)
Balance, shares at Dec. 31, 2018	108,691	108,691			4,584