Derivative Financial Instruments - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($) Instrument	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) Instrument	Jun. 30, 2018 USD ($)	Sep. 30, 2018 USD ($)
Derivative [Line Items]
Realized (gain) loss on derivatives net of accumulated other comprehensive loss to interest expense	$ (229,000)	$ (113,000)	$ (458,000)	$ (309,000)
Number of interest rate swaps held | Instrument	0		0
Interest Expense [Member]
Derivative [Line Items]
Realized (gain) loss on derivatives net of accumulated other comprehensive loss to interest expense		$ (100,000)	$ (100,000)
Senior Term Note Due July 1, 2026 [Member]
Derivative [Line Items]
Settlement of forward starting swap agreements			$ 9,200,000
Amortized period on interest expense			10 years
Interest Rate Swaps Settled in 2018 [Member]
Derivative [Line Items]
Derivative notional amount					$ 100,000,000
Realized (gain) loss on derivatives net of accumulated other comprehensive loss to interest expense			$ 0