Insurance Operations - Beginning and Ending Balances and Changes in DPAC (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Deferred Policy Acquisition Costs [Roll Forward]
DPAC, beginning of period	$ 103,527	$ 90,530	$ 91,882	$ 84,686
Capitalized Costs	58,727	48,783	164,700	140,998
Amortization of DPAC	(50,959)	(44,493)	(145,287)	(130,864)
DPAC, end of period	$ 111,295	$ 94,820	$ 111,295	$ 94,820

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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 30
-Section 55
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121638166&loc=d3e11522-158419

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section 45
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6480726&loc=d3e6691-158385

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (g)(1)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(7)(a))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 30
-Section 50
-Paragraph 2B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121638524&loc=SL117422543-158416

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=35755530&loc=d3e11264-158415

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