New Accounting Pronouncements - Summary of Impact of Adopting New Lease Standards on Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Operating lease right-of-use asset, net	$ 145,574
Total assets	1,377,319		$ 1,183,031
Operating lease liability - current	28,647
Total current liabilities	311,122		321,314
Operating lease liability - non-current	138,373
Total non-current liabilities	442,710		268,054
Total liabilities and stockholders' equity	$ 1,377,319		$ 1,183,031
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Operating lease right-of-use asset, net		$ 148,884
Total assets		1,331,915
Operating lease liability - current		28,407
Total current liabilities		349,721
Operating lease liability - non-current		120,477
Total non-current liabilities		388,531
Total liabilities and stockholders' equity		1,331,915
Accounting Standards Update 2016-02 [Member] | New Lease Standard [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Operating lease right-of-use asset, net		148,884
Total assets		148,884
Operating lease liability - current		28,407
Total current liabilities		28,407
Operating lease liability - non-current		120,477
Total non-current liabilities		120,477
Total liabilities and stockholders' equity		$ 148,884