Compensation Plans (Schedule of Restricted Stock Units and Changes During the Year) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Restricted stock units weighted-average grant date fair value	$ 4.25	$ 3.48	$ 2.96
RSUs with Future Service Required Only [Member]
Restricted Stock Units, Nonvested, Number	2	5
Restricted Stock Units, Grants in Period	0
Restricted stock units weighted-average grant date fair value	$ 0.00
Restricted Stock Units, Nonvested, Weighted Average Grant Date Fair Value	$ 8.52	$ 7.03
Restricted Stock Units, Vested in Period	(3)
Restricted Stock Units, Vested in Period, Weighted Average Grant Date Fair Value	$ 6.1
Restricted Stock Units, Forfeited in Period	0
Restricted Stock Units, Forfeited in Period, Weighted Average Grant Date Fair Value	$ 0.00
RSUs with Future Performance and Service Required [Member]
Restricted Stock Units, Nonvested, Number	6	2
Restricted Stock Units, Grants in Period	4
Restricted stock units weighted-average grant date fair value	$ 4.21
Restricted Stock Units, Nonvested, Weighted Average Grant Date Fair Value	$ 3.95	$ 3.45
Restricted Stock Units, Vested in Period	0
Restricted Stock Units, Vested in Period, Weighted Average Grant Date Fair Value	$ 0.00
Restricted Stock Units, Forfeited in Period	0
Restricted Stock Units, Forfeited in Period, Weighted Average Grant Date Fair Value	$ 0.00