Accumulated Other Comprehensive Income (Loss) (AOCI balances) (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of	$ 2,916,782	$ 2,915,145	$ 2,452,941
Reclassification from accumulated other comprehensive income to retained earnings as a result of adoption of new guidance		(194,889)
Other Comprehensive Income (Loss), Net of Tax	99,466	(136,837)	228,136
As of	3,326,796	2,916,782	2,915,145
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of	203,829	535,555
Other comprehensive (loss) income before reclassifications	168,992	(105,634)
Net amount reclassified from accumulated other comprehensive income	(69,526)	(31,203)
Other Comprehensive Income (Loss), Net of Tax	99,466	(136,837)
As of	303,295	203,829	535,555
Foreign Currency Translation Adjustments [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of	(29,270)	6,314
Reclassification from accumulated other comprehensive income to retained earnings as a result of adoption of new guidance		0
Other comprehensive (loss) income before reclassifications	5,371	(35,584)	33,175
Net amount reclassified from accumulated other comprehensive income	2,011	0	137
Other Comprehensive Income (Loss), Net of Tax	7,382	(35,584)	33,312
As of	(21,888)	(29,270)	6,314
Unrealized Gains (Losses) on Available- for- Sale Securities [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of	0	194,889
Reclassification from accumulated other comprehensive income to retained earnings as a result of adoption of new guidance		(194,889)
Other comprehensive (loss) income before reclassifications	0	0
Net amount reclassified from accumulated other comprehensive income	0	0
Other Comprehensive Income (Loss), Net of Tax	0	0	67,252
As of	0	0	194,889
Unrealized Gain (Loss) on Pensions and Other Postretirement Plans [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of	232,836	334,536
Reclassification from accumulated other comprehensive income to retained earnings as a result of adoption of new guidance		0
Other comprehensive (loss) income before reclassifications	164,527	(70,629)
Net amount reclassified from accumulated other comprehensive income	(71,442)	(31,071)	(3,629)
Other Comprehensive Income (Loss), Net of Tax	93,085	(101,700)	127,479
As of	325,921	232,836	334,536
Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of	263	(184)
Reclassification from accumulated other comprehensive income to retained earnings as a result of adoption of new guidance		0
Other comprehensive (loss) income before reclassifications		579
Net amount reclassified from accumulated other comprehensive income		(132)
Other Comprehensive Income (Loss), Net of Tax		447	93
As of		$ 263	$ (184)
Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive (loss) income before reclassifications	(906)
Net amount reclassified from accumulated other comprehensive income	(95)
Other Comprehensive Income (Loss), Net of Tax	(1,001)
As of	$ (738)