Income Taxes - Net Operating Losses Carryforwards Expire (Detail) $ in Thousands	12 Months Ended
Dec. 31, 2020 USD ($)
Operating Loss Carryforwards [Line Items]
U.S. loss carryforwards	$ 0
State loss carryforwards	$ 95,552
U.S. federal \| Minimum
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, expiration year	2032
U.S. federal \| Maximum
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, expiration year	2035
California (U.S.) \| Minimum
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, expiration year	2017
California (U.S.) \| Maximum
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, expiration year	2036

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32621-109319

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 25
-Paragraph 20
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=117330534&loc=d3e28680-109314

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32632-109319

Name:	us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsDomestic
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant