Other Comprehensive Income (Loss) - Changes in AOCI Balances by Component (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	$ 1,210,165	$ 2,976,717	$ 1,584,092	$ 2,980,253
Total OCI, net of tax	23,138	(12,724)	(100,559)	32,671
Balance, end of year	1,230,894	2,498,738	1,230,894	2,498,738
AOCI, Net
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	(499,353)	(498,621)	(379,873)	(543,531)
Other comprehensive income (loss) before reclassifications	19,012	(15,234)	(101,436)	26,709
Amounts reclassified from AOCI	1,705	2,789	2,673	5,756
Total OCI, net of tax	20,717	(12,445)	(98,763)	32,465
Balance, end of year	(478,636)	(511,066)	(478,636)	(511,066)
Foreign Currency Translation
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	(349,834)	(268,089)	(242,950)	(309,800)
Other comprehensive income (loss) before reclassifications	28,651	(14,257)	(78,233)	27,454
Amounts reclassified from AOCI	0	0	0	0
Total OCI, net of tax	28,651	(14,257)	(78,233)	27,454
Balance, end of year	(321,183)	(282,346)	(321,183)	(282,346)
Ownership Share of Equity Method Investees’ Other Comprehensive Income (Loss)
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	(43,628)	(25,994)	(35,456)	(23,672)
Other comprehensive income (loss) before reclassifications	(10,786)	(2,606)	(19,099)	(5,070)
Amounts reclassified from AOCI	132	141	273	283
Total OCI, net of tax	(10,654)	(2,465)	(18,826)	(4,787)
Balance, end of year	(54,282)	(28,459)	(54,282)	(28,459)
Defined Benefit Pension and Postretirement Plans
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	(98,151)	(202,585)	(99,197)	(204,649)
Other comprehensive income (loss) before reclassifications	1	0	1	0
Amounts reclassified from AOCI	954	2,039	2,000	4,103
Total OCI, net of tax	955	2,039	2,001	4,103
Balance, end of year	(97,196)	(200,546)	(97,196)	(200,546)
Unrealized Gain (Loss) on Derivative Contracts
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	(7,740)	(1,953)	(2,270)	(5,410)
Other comprehensive income (loss) before reclassifications	1,146	1,629	(4,105)	4,325
Amounts reclassified from AOCI	619	609	400	1,370
Total OCI, net of tax	1,765	2,238	(3,705)	5,695
Balance, end of year	(5,975)	285	(5,975)	285
AOCI, Net
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	(9,268)	(3,216)	(5,051)	(3,701)
Other comprehensive income (loss) before reclassifications	2,421	(279)	(1,796)	206
Amounts reclassified from AOCI	0	0	0	0
Total OCI, net of tax	2,421	(279)	(1,796)	206
Balance, end of year	(6,847)	(3,495)	(6,847)	(3,495)
Foreign Currency Translation
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	(9,268)	(3,216)	(5,051)	(3,701)
Other comprehensive income (loss) before reclassifications	2,421	(279)	(1,796)	206
Amounts reclassified from AOCI	0	0	0	0
Total OCI, net of tax	2,421	(279)	(1,796)	206
Balance, end of year	(6,847)	(3,495)	(6,847)	(3,495)
Ownership Share of Equity Method Investees’ Other Comprehensive Income (Loss)
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	0	0	0	0
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from AOCI	0	0	0	0
Total OCI, net of tax	0	0	0	0
Balance, end of year	0	0	0	0
Defined Benefit Pension and Postretirement Plans
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	0	0	0	0
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from AOCI	0	0	0	0
Total OCI, net of tax	0	0	0	0
Balance, end of year	0	0	0	0
Unrealized Gain (Loss) on Derivative Contracts
Changes in AOCI balances by component (after-tax)
Balance, beginning of year	0	0	0	0
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from AOCI	0	0	0	0
Total OCI, net of tax	0	0	0	0
Balance, end of year	$ 0	$ 0	$ 0	$ 0

Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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