Stock-Based Employee Compensation Plans - Additional Information With Respect to Restricted Stock Units and Performance Units (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of number of shares that may be earned related to performance units, Minimum	0.00%
Percentage of number of shares that may be earned related to performance units, Maximum	200.00%
Percentage of performance units earned as it relates to vested shares	155.20%
Number of performance units earned as it relates to vested shares	936,300