Accumulated Other Comprehensive Loss (Changes in Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	$ 1,839,654	$ 2,909,286	$ 3,009,486
Other comprehensive (loss) income before reclassifications	54,363	(116,986)	(306,040)
Income tax	(24,644)	18,384	108,225
Net other comprehensive (loss) income before reclassifications	29,719	(98,602)	(197,815)
Reclassifications	31,934	(2,636)	24,695
Net reclassifications	20,105	(1,660)	15,548
Total other comprehensive income (loss), net of tax	49,824	(100,262)	(182,267)
Balance, end of period	1,920,158	1,839,654	2,909,286
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(615,205)	(514,943)	(332,676)
Income tax expense (benefit)	(11,829)	976	(9,147)
Total other comprehensive income (loss), net of tax	49,824	(100,262)	(182,267)
Balance, end of period	(565,381)	(615,205)	(514,943)
Foreign currency translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(58,844)	(3,482)	33,326
Other comprehensive (loss) income before reclassifications	(7,591)	(48,309)	(50,310)
Income tax	(1,697)	(7,053)	13,502
Net other comprehensive (loss) income before reclassifications	(9,288)	(55,362)	(36,808)
Reclassifications	0	0	0
Income tax expense (benefit)	0	0	0
Net reclassifications	0	0	0
Total other comprehensive income (loss), net of tax	(9,288)	(55,362)	(36,808)
Balance, end of period	(68,132)	(58,844)	(3,482)
Marketable securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(1,094)	(700)	(276)
Other comprehensive (loss) income before reclassifications	(159)	(626)	(673)
Income tax	59	232	249
Net other comprehensive (loss) income before reclassifications	(100)	(394)	(424)
Reclassifications	0	0	0
Income tax expense (benefit)	0	0	0
Net reclassifications	0	0	0
Total other comprehensive income (loss), net of tax	(100)	(394)	(424)
Balance, end of period	(1,194)	(1,094)	(700)
Derivative financial instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	5,886	19,042	(1,680)
Other comprehensive (loss) income before reclassifications	28,176	38,008	46,775
Income tax	(10,436)	(14,079)	(17,325)
Net other comprehensive (loss) income before reclassifications	17,740	23,929	29,450
Reclassifications	(17,633)	(58,902)	(13,863)
Income tax expense (benefit)	6,531	21,817	5,135
Net reclassifications	(11,102)	(37,085)	(8,728)
Total other comprehensive income (loss), net of tax	6,638	(13,156)	20,722
Balance, end of period	12,524	5,886	19,042
Derivative financial instruments | Foreign currency contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassifications	(18,253)	(59,730)	(13,635)
Derivative financial instruments | Commodity contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassifications	258	677	(228)
Derivative financial instruments | Treasury rate locks
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassifications	362	151
Pension and postretirement benefit plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(561,153)	(529,803)	(364,046)
Other comprehensive (loss) income before reclassifications	33,937	(106,059)	(301,832)
Income tax	(12,570)	39,284	111,799
Net other comprehensive (loss) income before reclassifications	21,367	(66,775)	(190,033)
Reclassifications	49,567	56,266	38,558
Income tax expense (benefit)	(18,360)	(20,841)	(14,282)
Net reclassifications	31,207	35,425	24,276
Total other comprehensive income (loss), net of tax	52,574	(31,350)	(165,757)
Balance, end of period	(508,579)	(561,153)	(529,803)
Pension and postretirement benefit plans; Prior service credits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassifications	(1,784)	(2,782)	(2,734)
Pension and postretirement benefit plans; Actuarial losses
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassifications	49,888	58,680	$ 41,292
Pension and postretirement benefit plans; Curtailment and settlement losses
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassifications	$ 1,463	$ 368