Equity - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended							0 Months Ended					12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Minimum	Dec. 31, 2013 Maximum	Dec. 31, 2013 Unvested Stock Options	Dec. 31, 2012 Restricted Stock	Feb. 08, 2014 BOD authorized plan	Dec. 12, 2012 BOD authorized plan	Feb. 08, 2014 Rule 10b5-1 plan [Member]	Aug. 14, 2013 Rule 10b5-1 plan [Member]	Dec. 31, 2013 Employee Stock Purchase Plan	Dec. 31, 2013 Shareholder Rights Plan
Equity [Line Items]
Authorized amount under share repurchase program									$ 50.0		$ 36.2
Share repurchase plan commencement date									Dec. 12, 2012		Aug. 14, 2013
Share repurchase plan expiration date								Feb. 07, 2014		Feb. 07, 2014
Term of plan, in years	10 years
Weighted average remaining contractual term option outstanding	3 years 11 months
Weighted average remaining contractual term option exercisable	2 years 5 months
Shares available for future grants	6,800,000	7,700,000	8,600,000									500,000
Total pre-tax intrinsic value of stock options exercised	1.8	6.7
Total pre-tax intrinsic value based on the closing stock price	$ 11.59
Intrinsic value of stock options outstanding	6.7
Intrinsic value of stock options exercisable	4.8
Common shares reserved for future issuance under the ESPP	4,000,000
Percentage of employee contribution from compensation	10.00%
Rate of discount from the fair market value	15.00%
Shares issued under the ESPP	3,500,000
Shares purchase by employees	200,000	300,000	400,000
Weighted-average price per share paid by the employees	$ 8.00	$ 7.34	$ 4.35
Weighted average remaining contractual term for unvested restricted shares, in years	2 years	1 year 10 months
Total compensation cost not yet recognized						$ 3.1	$ 9.8
Compensation cost expected to be recognized (in years)	2 years 5 months
Share-based payment awards in the form of stock option awards	553,000	470,000	511,000
Vesting period, in years				3 years	4 years
Contractual term of stock options (in years)	7 years
Shares entitled to be purchased of a series of preferred stock under each right													one-hundredth
Exercise price under the shareholder rights plan													$ 50
Redemption of rights													$ 0.01
Percentage of common shares outstanding													15.00%