Operating Segments and Geographic Information (Information Related To Reportable Operating Business Segments) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Total consolidated revenues	$ 199,112	$ 243,273	$ 313,221	$ 267,907	$ 187,417	$ 245,888	$ 323,828	$ 279,140	$ 1,023,513	$ 1,036,273	$ 1,090,630
Income (loss) from operations	(30,377)	$ 2,685	$ 29,446	$ 15,582	(39,787)	$ (1,215)	$ 20,605	$ 14,243	17,336	(6,154)	(72,324)
Foreign currency gain (loss), net									563	(2,454)	(3,332)
Interest income									870	692	967
Interest expense									(869)	(836)	(969)
Other income, net									280	1,539	914
Income (loss) before income taxes									18,180	(7,213)	(74,744)
Total consolidated depreciation and amortization									33,130	34,043	35,993
Total long-lived assets	93,147				118,270				93,147	118,270
Total consolidated assets	543,695				566,390				543,695	566,390
Total property and equipment, net	35,032				44,090				35,032	44,090
Reportable Operating Segments [Member]
Segment Reporting Information [Line Items]
Total consolidated revenues									1,022,643	1,035,528	1,089,534
Income (loss) from operations									191,889	155,508	113,498
Total consolidated depreciation and amortization									10,815	12,184	13,543
Total long-lived assets	25,909				34,021				25,909	34,021
Total consolidated assets	396,824				424,160				396,824	424,160
Reportable Operating Segments [Member] | Americas
Segment Reporting Information [Line Items]
Total consolidated revenues									480,146	467,006	476,210
Income (loss) from operations									86,880	58,844	49,422
Total consolidated depreciation and amortization									5,473	5,787	7,401
Reportable Operating Segments [Member] | Americas [Member]
Segment Reporting Information [Line Items]
Total long-lived assets	17,129				22,406				17,129	22,406
Total consolidated assets	158,641				181,404				158,641	181,404
Reportable Operating Segments [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Total consolidated revenues									369,667	395,078	424,491
Income (loss) from operations									79,273	78,907	48,447
Total consolidated depreciation and amortization									3,464	4,264	3,913
Total long-lived assets	4,171				6,524				4,171	6,524
Total consolidated assets	161,646				154,862				161,646	154,862
Reportable Operating Segments [Member] | Europe [Member]
Segment Reporting Information [Line Items]
Total consolidated revenues									172,830	173,444	188,833
Income (loss) from operations									25,736	17,757	15,629
Total consolidated depreciation and amortization									1,878	2,133	2,229
Total long-lived assets	4,609				5,091				4,609	5,091
Total consolidated assets	76,537				87,894				76,537	87,894
Reportable Operating Segments [Member] | Other businesses [Member]
Segment Reporting Information [Line Items]
Total consolidated revenues									870	745	1,096
Income (loss) from operations									(22,861)	(26,935)	(30,092)
Total consolidated depreciation and amortization									6,748	6,830	7,634
Unallocated corporate
Segment Reporting Information [Line Items]
Income (loss) from operations									(151,692)	(134,727)	(155,730)
Total consolidated depreciation and amortization									15,567	15,029	14,816
Total long-lived assets	49,842				62,377				49,842	62,377
Total consolidated assets	109,078				99,191				109,078	99,191
UNITED STATES
Segment Reporting Information [Line Items]
Total consolidated revenues									388,847	384,939	392,463
Total property and equipment, net	23,396				29,420				23,396	29,420
Non-US [Member]
Segment Reporting Information [Line Items]
Total consolidated revenues									634,666	651,334	$ 698,167
Total property and equipment, net	11,636				14,670				11,636	14,670
Supply Chain [Member]
Segment Reporting Information [Line Items]
Total long-lived assets	17,396				21,872				17,396	21,872
Total consolidated assets	$ 37,793				$ 43,039				$ 37,793	$ 43,039