Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax [Line Items]
Federal corporate tax rate		35.00%
Benefit recognized from tax cuts and jobs act		$ 33,910,000
Interest related to unrecognized tax benefits		0	$ 100,000	$ 200,000
Accrued interest and penalties related to unrecognized tax benefits		100,000	600,000
Unrecognized tax benefits that would affect the Company's effective tax rate if recognized		1,100,000	1,300,000
Cash (received) paid for income taxes		17,000,000	5,400,000	$ 16,400,000
Tax credit recognized			$ 1,000,000
Accounting Standards Update 2016-09 [Member]
Income Tax [Line Items]
Benefit related to excess tax benefits from stock activity		$ 1,700,000
Maximum [Member]
Income Tax [Line Items]
Income tax year open for examination		2017
Maximum [Member] | State and Local Jurisdiction [Member]
Income Tax [Line Items]
Income tax year open for examination		2017
Minimum [Member]
Income Tax [Line Items]
Income tax year open for examination		2015
Minimum [Member] | State and Local Jurisdiction [Member]
Income Tax [Line Items]
Income tax year open for examination		2008
Scenario Forecast [Member]
Income Tax [Line Items]
Federal corporate tax rate	21.00%