Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Change in uncertain tax positions		$ 0	$ 300,000	$ 3,000,000
Cash paid for income taxes, net of refunds		46,700,000	29,300,000	24,100,000
Liability for uncertain tax positions		$ 3,000,000	$ 3,000,000	$ 3,300,000
Scenario, Forecast [Member]
Income Taxes [Line Items]
Effective corporate federal tax rate	21.00%