Summary of Significant Accounting Policies - Summary of Lease Exit Accruals (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($)
Accounting Policies [Abstract]
Beginning balance	$ 9,790
Lease exit expense	1,827
Payments	(1,877)
Other	(1,377)
Ending balance	$ 8,363