Shareholders' Equity Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	$ (229,327)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	58,849	$ (28,720)	$ (65,547)
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(170,478)	(229,327)
Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(229,327)	(200,607)	(135,060)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	56,568	(30,848)	(69,245)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	2,281	2,128	3,698
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	58,849	(28,720)	(65,547)
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(170,478)	(229,327)	(200,607)
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(182,986)	(158,009)	(85,080)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	53,854	(23,570)	(73,891)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	484	(1,407)	962
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	54,338	(24,977)	(72,929)
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(128,648)	(182,986)	(158,009)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	43	318	(768)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	360	(1,087)	76
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	563	812	1,010
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	923	(275)	1,086
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	966	43	318
Accumulated Other Comprehensive Income, Net Unrealized Gain (Loss) on Nonderivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(14,380)	(14,380)	(14,380)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	0	0	0
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(14,380)	(14,380)	(14,380)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(32,004)	(28,536)	(34,832)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	2,354	(6,191)	4,570
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	1,234	2,723	1,726
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	3,588	(3,468)	6,296
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	$ (28,416)	$ (32,004)	$ (28,536)