Shareholders' Equity Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period			$ (170,478)
Total other comprehensive income (loss), net of tax	$ (33,273)	$ 20,409	(15,390)	$ 36,118
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(185,868)		(185,868)
Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period			(170,478)	(229,327)
OCI before reclassifications			(13,782)	35,133
Amounts reclassified from AOCI			(1,608)	985
Total other comprehensive income (loss), net of tax			(15,390)	36,118
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(185,868)	(193,209)	(185,868)	(193,209)
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period			(128,648)	(182,986)
OCI before reclassifications			(17,860)	35,463
Amounts reclassified from AOCI			0	0
Total other comprehensive income (loss), net of tax			(17,860)	35,463
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(146,508)	(147,523)	(146,508)	(147,523)
Accumulated Other Comprehensive Income, Net Unrealized Gain (Loss) on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period			966	43
OCI before reclassifications			4,078	(330)
Amounts reclassified from AOCI			(2,423)	391
Total other comprehensive income (loss), net of tax			1,655	61
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	2,621	104	2,621	104
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)
OCI before reclassifications			0	0
Amounts reclassified from AOCI			0	0
Total other comprehensive income (loss), net of tax			0	0
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(14,380)	(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			(28,416)	(32,004)
OCI before reclassifications			0	0
Amounts reclassified from AOCI			815	594
Total other comprehensive income (loss), net of tax			815	594
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	$ (27,601)	$ (31,410)	$ (27,601)	$ (31,410)