Other Current and Non-Current Liabilities - Schedule of Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Other Liabilities Disclosure [Abstract]
Accrued accounts payable	$ 38,046	$ 24,119
Accrued compensation liability	33,815	22,554
Accrued restructuring liability	3,674	4,987
Accrued payable from acquisitions	12,800	5,990
Accrued lease incentive obligation	20,059
Other current liabilities	14,695	18,104
Total other current liabilities	$ 123,089	$ 75,754