Certain Employee Benefit and Stock-Based Compensation Plans (Summary of Nonvested Incentive/Performance Unit Share Awards and Restricted Stock/Unit Awards-Rollforward) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Nonvested Incentive Performance Unit Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested Cash-Payable Restricted Unit Shares, Beginning balance	830
Granted	465
Vested/released	(100)
Forfeited	(34)
Nonvested Cash-Payable Restricted Unit Shares, Ending balance	1,161
Weighted-average grant date fair value, beginning of period	$ 61.68
Weighted-average grant date fair value, granted shares	$ 60.70
Weighted-average grant date fair value, vested/released shares	$ 64.21
Weighted-average grant date fair value, forfeited shares	$ 62.44
Weighted-average grant date fair value, end of period	$ 61.05
Nonvested Restricted Stock Unit Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested Cash-Payable Restricted Unit Shares, Beginning balance	2,512
Granted	1,455
Vested/released	(789)
Forfeited	(115)
Nonvested Cash-Payable Restricted Unit Shares, Ending balance	3,063
Weighted-average grant date fair value, beginning of period	$ 54.87
Weighted-average grant date fair value, granted shares	$ 61.03
Weighted-average grant date fair value, vested/released shares	$ 45.44
Weighted-average grant date fair value, forfeited shares	$ 60.86
Weighted-average grant date fair value, end of period	$ 60.00