Stock-based Compensation - Additional Information (Detail) (USD $)	6 Months Ended					1 Months Ended
	Jun. 30, 2013	Jun. 30, 2013 Employee Stock Option	Jun. 30, 2013 Acquired to satisfy the exercise price Employee Stock Option	Jun. 30, 2013 Acquired to satisfy payroll tax withholding obligations Employee Stock Option	Jun. 30, 2013 Performance Unit Awards 2010	Apr. 30, 2013 Performance Unit Awards 2010 Scenario, Forecast
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Treasury stock shares acquired		637,624
Treasury stock acquisition price	$ 22,358,000		$ 12,300,000	$ 2,900,000
Performance period					3 years
Award description					Generally, the recipients will receive a target number of shares if the Company's total shareholder return is positive and, when compared to the peer group, is at the 50thpercentile and two times the target if at the 75thpercentile or higher.
Target number of shares					178,750
Shares issued						357,500