Stockholders' Equity - Additional Information (Detail) - 2016 Share Repurchase Program [Member] - USD ($) $ / shares in Units, shares in Millions	3 Months Ended
	Mar. 31, 2017	Nov. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Repurchase of common stock	43.6
Treasury stock acquired, average cost per share	$ 2.72
Stock repurchase program, aggregate number of shares repurchased value	$ 118,700,000
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program, authorized amount		$ 200,000,000
Common Class A [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Repurchase of common stock	31.2
Treasury stock acquired, average cost per share	$ 2.70
Stock repurchase program, aggregate number of shares repurchased value	$ 84,500,000