Summary of Significant Accounting Policies - Components of Other Long-Term Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Post-employment and other benefit/retirement liabilities	$ 60,458	$ 56,723
Insurance liabilities	44,181	37,608
Other lease obligations	55,693	39,221
Other taxes payable	47,724	16,997
Customer deposits	65,758	79,528
Guarantees related to borrowings	65,000	42,000
Other	162,190	195,981
Total other long-term liabilities	$ 501,004	$ 468,058