Share-Based Payments - Additional Information (Detail)	3 Months Ended		1 Months Ended		1 Months Ended			3 Months Ended
	Dec. 31, 2013 OptionPlan	Sep. 30, 2013	Nov. 30, 2013 Market Share Units ("MSUs")	Dec. 31, 2013 Market Share Units ("MSUs")	Nov. 30, 2013 Market Share Units ("MSUs") Performance Period 1	Nov. 30, 2013 Market Share Units ("MSUs") Performance Period 2	Nov. 30, 2013 Market Share Units ("MSUs") Performance Period 3	Dec. 31, 2013 2012 Long-Term Incentive Plan Restricted Stock Unit Awards Subject to Market Conditions	Dec. 31, 2013 2012 Long-Term Incentive Plan Maximum Awards Granted After September 30, 2005	Dec. 31, 2013 2012 Long-Term Incentive Plan Maximum Awards Granted Prior to October 1, 2005	Dec. 31, 2013 2012 Long-Term Incentive Plan Maximum Restricted Stock Unit Awards Not Subject to Market Conditions	Dec. 31, 2013 2012 Long-Term Incentive Plan Minimum Restricted Stock Unit Awards Not Subject to Market Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of incentive plans	3
Stock option awards term									7 years	10 years
Stock option awards vesting period								3 years			4 years	3 years
Performance based equity award, outstanding	674,000		88,000
Performance based equity award, required performance period					P1Y	P2Y	P3Y
Performance based equity award, outstanding	1,940,000	1,716,000		88,000