Share-Based Payments (Narrative) (Detail) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock options (in years)	3 years
Common share equivalents subject to and available for distribution to recipients	100
Share equivalents factor, restricted stock granted	2.25
Share equivalent factor stock options	1
Number of remaining share equivalents authorized for issuance under the long term compensation plan	66
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of years within the adoption of stock option and long-term incentive compensation plans that awards may be granted	10 years
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of years within the adoption of stock option and long-term incentive compensation plans that awards may be granted	7 years