Significant Accounting Policies - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2019	Jan. 01, 2019
Accounting Policies [Abstract]
Right-of-use asset	$ 257,600,000	$ 274,700,000
Operating Lease Right Of Use Asset Statement Of Financial Position Extensible List	us-gaap:OtherAssets	us-gaap:OtherAssetsNoncurrent
Lease liabilities, current	$ 62,500,000	$ 62,200,000
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent	us-gaap:OtherLiabilitiesCurrent
Lease liabilities, noncurrent	$ 205,400,000	$ 221,200,000
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Cumulative adjustment to retained earnings	$ 0