Summary of Liabilities Measured at Fair Value on a Recurring Basis (Detail) - Fair Value Measurements, Recurring - USD ($) $ in Thousands		Jun. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Interest rate swap liabilities	[1]	$ (17,280)	$ (5,093)
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Interest rate swap liabilities	[1]	$ (17,280)	$ (5,093)

[1]   (1) See further discussion of interest rate swaps at Note 6.