Income Taxes - Components of Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Current income tax expense (benefit)	$ 134,948	$ 134,626	$ 138,262
Deferred income tax expense (benefit)	35,449	27,535	(765,877)
Income Tax Expense (Benefit), Total	170,397	162,161	(627,615)
Shareholders’ equity:
Other comprehensive income (loss)	405,472	(293,678)	318,475
Income tax expense (benefit)	$ 575,869	$ (131,517)	$ (309,140)