Shareholders' Equity Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gain (loss) on hedging instruments at January 1,			$ (170,478)
Amounts reclassified from AOCI	$ 0	$ 1,089	0	$ 1,089
Total other comprehensive income (loss), net of tax	622	15,466	(14,768)	51,584
Net unrealized gain (loss) on hedging instruments at September 30,	(185,246)		(185,246)
Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gain (loss) on hedging instruments at January 1,			(170,478)	(229,327)
OCI before reclassifications			(13,768)	49,009
Amounts reclassified from AOCI			(1,000)	2,575
Total other comprehensive income (loss), net of tax			(14,768)	51,584
Net unrealized gain (loss) on hedging instruments at September 30,	(185,246)	(177,743)	(185,246)	(177,743)
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gain (loss) on hedging instruments at January 1,			(128,648)	(182,986)
OCI before reclassifications			(18,538)	49,304
Amounts reclassified from AOCI			0	1,089
Total other comprehensive income (loss), net of tax			(18,538)	50,393
Net unrealized gain (loss) on hedging instruments at September 30,	(147,186)	(132,593)	(147,186)	(132,593)
Accumulated Other Comprehensive Income, Net Unrealized Gain (Loss) on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gain (loss) on hedging instruments at January 1,			966	43
OCI before reclassifications			4,770	(295)
Amounts reclassified from AOCI			(2,207)	482
Total other comprehensive income (loss), net of tax			2,563	187
Net unrealized gain (loss) on hedging instruments at September 30,	3,529	230	3,529	230
Accumulated Other Comprehensive Income, Net Unrealized Gain (Loss) on Nonderivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gain (loss) on hedging instruments at January 1,			(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
Net unrealized gain (loss) on hedging instruments at September 30,	(14,380)	(14,380)	(14,380)	(14,380)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gain (loss) on hedging instruments at January 1,			(28,416)	(32,004)
OCI before reclassifications			0	0
Amounts reclassified from AOCI			1,207	1,004
Total other comprehensive income (loss), net of tax			1,207	1,004
Net unrealized gain (loss) on hedging instruments at September 30,	$ (27,209)	$ (31,000)	$ (27,209)	$ (31,000)