Derivatives - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Derivative Instruments [Line Items]
Estimate increase to interest expense	$ 4.0
Derivative, notional amount	748.6
Carrying Value Of Net Losses Associated With Interest Rate Swaps	$ 0.4
Interest Rate Swap [Member]
Derivative Instruments [Line Items]
Number of derivative, interest rate swap agreement	29
Derivative, Weighted average interest rate	1.48%
Derivative, notional amount	$ 748.6
Settled Interest Rate Swaps [Member]
Derivative Instruments [Line Items]
Amortization Period of Deferred Gain (Loss) on Discontinuation of Fair Value Hedge	10 years