Capital Stock and Share-Based Compensation (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Share-Based Awards [Member]	Dec. 31, 2013 Share Based Awards To More Than Ten Percent Owner [Member]	Dec. 31, 2013 Non-Vested Stock [Member]	Dec. 31, 2012 Non-Vested Stock [Member]	Dec. 31, 2011 Non-Vested Stock [Member]	Dec. 31, 2012 Non-Vested Stock Units - Service-Based and Performance-Based [Member]	Dec. 31, 2011 Non-Vested Stock Units - Service-Based and Performance-Based [Member]	Dec. 31, 2013 Non-Vested Stock Units - Service-Based and Market-Based [Member]	Dec. 31, 2013 Minimum [Member]	Dec. 31, 2013 Maximum [Member]	Jun. 07, 2012 Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common Stock Shares Authorized	60,000,000	60,000,000
Common Stock Par Or Stated Value Per Share	$ 0.001	$ 0.001
Preferred Stock Shares Authorized	5,000,000	5,000,000
Preferred Stock Par Or Stated Value Per Share	$ 0.001	$ 0.001
Common Stock Shares Issued	33,413,970	31,876,508
Common Stock Shares Outstanding	32,538,971	31,086,619
Preferred Stock Shares Issued	0	0
Preferred Stock Shares Outstanding	0	0
Percentage of Ownership in Subsidiaries	50.00%
Equity-based Awards, Maximum Number of Shares Granted	4,000,000
Equity-based Awards, Shares Available for Grant	1,700,000
Fair Value of Share of Common Stock, Percentage				100.00%	110.00%
Percentage of Total Combined Voting Power of the Ccompany and Our Subsidiaries	10.00%
Vesting Period of Equity-based Awards												12 months	5 years
Contractual Term of Stock Options Exercised													ten
Percentage of Market Value at Which Eligible Employees May Purchase Shares of Common Stock	85.00%
Common Stock Shares Authorized For Issuance To Employee Stock Purchase Plan													4,500,000	2,500,000
Stock Available For Future Issuance Under Employee Purchase Plan	1,744,663
Employee Stock Purchase Plan expense	$ 0.5	$ 0.7	$ 0.8
Intrinsic Value of Stock Options Outstanding	0.1
Intrinsic Value of Stock Options Exerciseable	0.1
Intrinsic Value of Stock Options Exercised	0.2	0.1	0.7
Stock Compensation Expense						5.2	6.4	7.2	0.1	0.3	0.8
Non-vested Stock Granted, Weighted Average Grant Date Fair Value						$ 10.91	$ 14.01	$ 27.05	$ 56.99	$ 27.40	$ 10.51
Unrecognized compensation expense related to non-vested stock awards						$ 4.0					$ 3.3
Non-vested stock award compensation expense weighted-average period, years						1 year 3 months 19 days					2 years 3 months 19 days
Market-based award, target number of shares to be received	417,330
Market-based award, maximum number of shares authorized to be received	667,728