Derivative Instruments and Hedging Activities - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2018 USD ($) Swap	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Ineffectiveness on cash flow hedges	$ 0	$ 0
Reclassified as an increase to interest expense, expected during the next 12 months	767,000
Termination value of derivatives in a net asset position	1,754,000
Interest Rate Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of interest rate swap	$ 1,000,000,000
Number of interest rate swaps held | Swap	5
Combined Interest Rate Cash Flow Hedges, All Swaps [Member] | Interest Rate Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of interest rate swap	$ 1,000,000,000
Number of interest rate swaps held | Swap	5
Not Designated as Hedge Accounting Relationships [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives outstanding	$ 0		$ 0