Deferred Policy Acquisition Costs - Deferred Policy Acquisition Costs (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)
Deferred Policy Acquisition Costs [Roll Forward]
Beginning balance	$ 1,423,007
Additions	134,665
Amortization	(132,993)
Effect of change in unrealized gains on available-for-sale debt securities	89,326
Net change	90,998
Ending balance	1,514,005
Life
Deferred Policy Acquisition Costs [Roll Forward]
Beginning balance	852,900
Additions	33,353
Amortization	(25,515)
Effect of change in unrealized gains on available-for-sale debt securities	7,619
Net change	15,457
Ending balance	868,357
Annuity
Deferred Policy Acquisition Costs [Roll Forward]
Beginning balance	415,380
Additions	11,525
Amortization	(18,811)
Effect of change in unrealized gains on available-for-sale debt securities	81,707
Net change	74,421
Ending balance	489,801
Health
Deferred Policy Acquisition Costs [Roll Forward]
Beginning balance	32,578
Additions	5,378
Amortization	(5,355)
Effect of change in unrealized gains on available-for-sale debt securities	0
Net change	23
Ending balance	32,601
Property & Casualty
Deferred Policy Acquisition Costs [Roll Forward]
Beginning balance	122,149
Additions	84,409
Amortization	(83,312)
Effect of change in unrealized gains on available-for-sale debt securities	0
Net change	1,097
Ending balance	$ 123,246