Supplemental Information about Changes to Accumulated Other Comprehensive Income - Schedule of Change in Balance by Component (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	$ 5,415,177	$ 6,231,421	$ 4,566,861
Other comprehensive income (loss) before reclassifications, net of tax	1,529,591	(1,115,335)	608,968
Reclassifications, net of tax	(4,236)	10,536	(14,668)
Other comprehensive income (loss)	1,525,355	(1,104,799)	594,300
Ending balance	7,294,307	5,415,177	6,231,421
Total
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	319,475	1,424,274	577,574
Reclassifications, tax reform			252,400
Ending balance	1,844,830	319,475	1,424,274
Available for Sale Assets
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	435,698	1,569,289	692,314
Other comprehensive income (loss) before reclassifications, net of tax	1,557,883	(1,132,202)	621,619
Reclassifications, net of tax	(10,931)	(1,389)	(22,751)
Other comprehensive income (loss)	1,546,952	(1,133,591)	598,868
Reclassifications, tax reform			278,107
Ending balance	1,982,650	435,698	1,569,289
Deferred Acquisition Costs
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(4,163)	(8,547)	(6,682)
Other comprehensive income (loss) before reclassifications, net of tax	(1,753)	4,384	(350)
Reclassifications, net of tax	0	0	0
Other comprehensive income (loss)	(1,753)	4,384	(350)
Reclassifications, tax reform			(1,515)
Ending balance	(5,916)	(4,163)	(8,547)
Foreign Exchange
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	6,495	16,302	4,967
Other comprehensive income (loss) before reclassifications, net of tax	5,563	(9,807)	8,452
Reclassifications, net of tax	0	0	0
Other comprehensive income (loss)	5,563	(9,807)	8,452
Reclassifications, tax reform			2,883
Ending balance	12,058	6,495	16,302
Pension Adjustments
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(118,555)	(152,770)	(113,025)
Other comprehensive income (loss) before reclassifications, net of tax	(32,102)	22,290	(20,753)
Reclassifications, net of tax	6,695	11,925	8,083
Other comprehensive income (loss)	(25,407)	34,215	(12,670)
Reclassifications, tax reform			(27,075)
Ending balance	$ (143,962)	$ (118,555)	$ (152,770)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Amount after tax of reclassification adjustments of other comprehensive income (loss) attributable to parent.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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Amount of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act.

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