Management Compensation Plans Management Compensation Plans (Schedule of Summary of Changes in Time-based RSUs Outstanding) (Details) (Time Restricted Stock Units (RSUs) [Member], USD $)	12 Months Ended
Dec. 31, 2011
Employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested at December 31, 2010, Number of Units	607,000
Granted, Number of Units	332,000
Vested, Number of Units	(213,000)
Forfeited, Number of Units	(44,000)
Nonvested at December 31, 2011, Number of Units	682,000
Nonvested at December 31, 2010, Weighted-Average Fair Value	$ 26.41
Granted, Weighted-Average Fair Value	$ 33.67
Vested, Weighted-Average Fair Value	$ 27.78
Forfeited, Weighted-Average Fair Value	$ 27.27
Nonvested at December 31, 2011, Weighted-Average Fair Value	$ 30.37
Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested at December 31, 2010, Number of Units	21,000
Granted, Number of Units	13,000
Vested, Number of Units	(21,000)
Forfeited, Number of Units	0
Nonvested at December 31, 2011, Number of Units	13,000
Nonvested at December 31, 2010, Weighted-Average Fair Value	$ 33.13
Granted, Weighted-Average Fair Value	$ 49.30
Vested, Weighted-Average Fair Value	$ 33.13
Forfeited, Weighted-Average Fair Value	$ 0
Nonvested at December 31, 2011, Weighted-Average Fair Value	$ 49.30

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References+ Details

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References+ Details

- Definition

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

+ References+ Details

- Definition

The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

+ References+ Details