Other Current and Non-Current Liabilities - Schedule of Other Current Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Other Liabilities Current [Abstract]
Accrued accounts payable	$ 42,703	$ 22,669
Accrued compensation liability	28,568	41,554
Accrued restructuring liability		3,449
Contingent consideration payable	94,900	17,300
Accrued payable from acquisitions	35,000	35,000
Accrued lease incentive obligation	43,787	24,895
Value-added taxes payable	2,186	2,624
Other current liabilities	10,096	9,338
Total other current liabilities	$ 257,240	$ 156,829