Capital Requirements and Restriction on Retained Earnings - Additional Information (Detail) $ in Thousands	12 Months Ended
Dec. 31, 2018 USD ($)
Capital Requirements And Restriction On Retained Earnings [Abstract]
Net profits available to pay dividends to CBI	$ 50,821

Amount after tax of income (loss) of subsidiary attributable to the parent entity.

No definition available.

Name:	us-gaap_IncomeLossFromSubsidiariesNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration