Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Balances for Each Component of Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, at beginning of period			$ 1,257,455
Other comprehensive income (loss) before reclassifications	$ (13,274)	$ 8,952	(70,575)	$ 70,361
Amounts reclassified from accumulated other comprehensive income (loss)	2,330	10,450	17,339	10,136
Net increase (decrease) in other comprehensive income (loss)	(10,944)	19,402	(53,236)	80,497
Accumulated Other Comprehensive Income (Loss), Net of Tax, at end of period	666,410	1,439,675	666,410	1,439,675
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, at beginning of period	(824,078)	(881,934)	(781,786)	(943,029)
Accumulated Other Comprehensive Income (Loss), Net of Tax, at end of period	(835,022)	(862,532)	(835,022)	(862,532)
Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, at beginning of period	452	(25,114)	(21,098)	17,469
Other comprehensive income (loss) before reclassifications	3,215	(24,009)	15,548	(63,999)
Amounts reclassified from accumulated other comprehensive income (loss)	787	9,241	10,004	6,648
Net increase (decrease) in other comprehensive income (loss)	4,002	(14,768)	25,552	(57,351)
Accumulated Other Comprehensive Income (Loss), Net of Tax, at end of period	4,454	(39,882)	4,454	(39,882)
Available-for-sale security
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, at beginning of period	(5,588)	(588)	(2,799)	3,149
Other comprehensive income (loss) before reclassifications	424	(3,848)	(2,365)	(7,585)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Net increase (decrease) in other comprehensive income (loss)	424	(3,848)	(2,365)	(7,585)
Accumulated Other Comprehensive Income (Loss), Net of Tax, at end of period	(5,164)	(4,436)	(5,164)	(4,436)
Defined Benefit Pension Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, at beginning of period	(140,528)	(155,625)	(143,213)	(157,704)
Other comprehensive income (loss) before reclassifications	219	(103)	(2,888)	(303)
Amounts reclassified from accumulated other comprehensive income (loss)	1,543	1,209	7,335	3,488
Net increase (decrease) in other comprehensive income (loss)	1,762	1,106	4,447	3,185
Accumulated Other Comprehensive Income (Loss), Net of Tax, at end of period	(138,766)	(154,519)	(138,766)	(154,519)
Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, at beginning of period	(678,414)	(700,607)	(614,676)	(805,943)
Other comprehensive income (loss) before reclassifications	(17,132)	36,912	(80,870)	142,248
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Net increase (decrease) in other comprehensive income (loss)	(17,132)	36,912	(80,870)	142,248
Accumulated Other Comprehensive Income (Loss), Net of Tax, at end of period	$ (695,546)	$ (663,695)	$ (695,546)	$ (663,695)