Stockholders' Equity - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 27, 2016
Equity [Line Items]
Preferred stock shares	25,000,000
Shares repurchased during the period, shares	3,980,656	0	0
Shares repurchased during the period, value	$ 161,034,000
Class A Common Stock [Member]
Equity [Line Items]
Authorized share repurchase term	3 years
Shares repurchased during the period, value	$ 40,000
Average price per share	$ 40.43	$ 0	$ 0
Class A Common Stock [Member] | Maximum [Member]
Equity [Line Items]
Authorized share repurchase amount				$ 250,000,000