Stock-Based Compensation - Additional Information (Detail) $ / shares in Units, $ in Millions		1 Months Ended			12 Months Ended
	Aug. 11, 2017 shares	Feb. 29, 2016 shares	Feb. 28, 2015 shares	Mar. 31, 2014 shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Sep. 05, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Special cash dividend paid | $					$ 140.0
Dividend payable date					May 26, 2017
Dividend payable, date of record					May 17, 2017
Incremental compensation expense | $					$ 6.9
Reverse stock split description	Reverse Split, every ten shares of common stock issued and outstanding was converted into one share of common stock				Reverse Split, every ten shares of common stock issued and outstanding was converted into one share of common stock
Reverse stock split, conversion ratio	0.1
Common stock, shares issued	132,800,000				13,343,000	13,020,000		13,280,000
Common stock, shares outstanding	132,800,000				13,343,000	13,020,000		13,280,000
Common stock, shares authorized	200,000,000				20,000,000	20,000,000		20,000,000
Number of fractional shares issued								0
Preferred stock, shares issued					0	0		0
Preferred stock, shares outstanding					0	0		0
Number of Options, Granted					2,111,000
Weighted-average grant date fair value per share of stock options | $ / shares					$ 4.07	$ 58.00	$ 34.10
Aggregate intrinsic value of options exercised | $					$ 2.4	$ 5.6	$ 30.9
Unrecognized stock-based compensation expense related to nonvested stock options | $					$ 5.0
Weighted average period over which unrecognized stock-based compensation expense is expected to be recognized					2 years 6 months 29 days
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term					10 years
Stock Incentive Plan 2011 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional common stock available for issuance (in shares)		400,000	400,000	400,000
Shares of common stock available for grant (in shares)					400,000
Number of Options, Granted					2,100,000	400,000	400,000
Stock Incentive Plan 2011 [Member] | Employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vesting period					3 years