Commitments and Contingencies - Annual Future Minimum Payments Under Operating Leases / Facility Exit Obligation (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Operating Leases
2018	$ 44,713
2019	47,986
2020	48,218
2021	45,590
2022	43,238
Thereafter	124,114
Operating leases, net of sublease income, total	353,859
Purchase Obligations
2018	31,394
2019	22,698
2020	11,736
2021	7,248
2022	3,805
Thereafter	4,093
Purchase obligation, total	80,974
Other
2018	574
2019	574
2020	574
2021	574
2022	574
Thereafter	1,053
Other commitment, total	3,923
Total
2018	76,681
2019	71,258
2020	60,528
2021	53,412
2022	47,617
Thereafter	129,260
Total minimum lease payments	438,756
Operating leases, cancellation penalty	$ 13,900