Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Accrual for the probable payment of pending claims	$ 52,801
Rent expense	$ 38,179	$ 36,537	$ 22,534

Amount of loss contingency liability.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

Name:	us-gaap_LossContingencyAccrualAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant