Supplemental Stockholders' Equity Information - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2015
Class of Stock [Line Items]
Stock repurchase program, remaining authorized repurchase amount	$ 16,200,000
Class A Common Stock
Class of Stock [Line Items]
Stock repurchase program, authorized amount		$ 101,100,000
Share repurchases	$ 84,900,000