Accumulated Other Comprehensive Income (Loss) (AOCI balances) (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income, beginning balance			$ 2,452,941
Other Comprehensive Income (Loss), Net of Tax	$ 39,245	$ 7,205	74,666	$ (330)
Accumulated Other Comprehensive Income, ending balance	2,560,677		2,560,677
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income, beginning balance			236,486
Other comprehensive (loss) income before reclassifications			77,328
Net amount reclassified from accumulated other comprehensive income			(2,662)
Other Comprehensive Income (Loss), Net of Tax			74,666
Accumulated Other Comprehensive Income, ending balance	311,152		311,152
Cumulative Foreign Currency Translation Adjustment [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income, beginning balance			(26,998)
Other comprehensive (loss) income before reclassifications	11,470	(353)	34,776	(1,629)
Net amount reclassified from accumulated other comprehensive income			0
Other Comprehensive Income (Loss), Net of Tax			34,776
Accumulated Other Comprehensive Income, ending balance	7,778		7,778
Unrealized Gain on Available-for-Sale Securities [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income, beginning balance			92,931
Other comprehensive (loss) income before reclassifications	28,702	7,292	42,822	4,314
Net amount reclassified from accumulated other comprehensive income			0	(3,754)
Other Comprehensive Income (Loss), Net of Tax			42,822	560
Accumulated Other Comprehensive Income, ending balance	135,753		135,753
Unrealized Gain on Pensions and Other Postretirement Plans [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income, beginning balance			170,830
Other comprehensive (loss) income before reclassifications			0
Net amount reclassified from accumulated other comprehensive income	(869)	237	(2,760)	710
Other Comprehensive Income (Loss), Net of Tax	(869)	237	(2,760)	710
Accumulated Other Comprehensive Income, ending balance	168,070		168,070
Cash Flow Hedge [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income, beginning balance			(277)
Other comprehensive (loss) income before reclassifications			(270)
Net amount reclassified from accumulated other comprehensive income			98
Other Comprehensive Income (Loss), Net of Tax	(58)	$ 29	(172)	$ 29
Accumulated Other Comprehensive Income, ending balance	$ (449)		$ (449)