Insurance Operations - Beginning and Ending Balances and Changes in DPAC (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Deferred Policy Acquisition Costs [Roll Forward]
DPAC, beginning of period	$ 83,284	$ 78,007	$ 84,686	$ 73,059
Capitalized Costs	50,694	50,430	92,215	92,369
Amortization of DPAC	(43,448)	(39,681)	(86,371)	(76,672)
DPAC, end of period	$ 90,530	$ 88,756	$ 90,530	$ 88,756

Amount of amortization expense (reversal of expense) for deferred policy acquisition costs.

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Name:	us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration