Financial Guarantees - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Financial Guarantees [Line Items]
Term of standby letters of credit, years	1 year
Notional amount of standby letters of credit	$ 100,200,000	$ 319,000,000.0
Carrying value of letters of credit	500,000	500,000
Notional amount	1,332,000,000	$ 1,482,000,000
Interest Rate Swap [Member]
Financial Guarantees [Line Items]
Notional amount	$ 38,300,000