Equity Incentive Compensation Plans (Restricted Stock Units and Performance Share Program) (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended				3 Months Ended		1 Months Ended
	Mar. 31, 2012 year	Mar. 31, 2012 Restricted Stock Units year	Mar. 31, 2012 Restricted Stock Units Executive officers and other officers	Mar. 31, 2012 Restricted Stock Units Non-employee directors	Mar. 31, 2012 Performance-Based RSUs ratio year simulation		Mar. 31, 2012 Performance-Based RSUs Executive officers and other officers
Equity Incentive Compensation Plans
Fully Vested Shares Outstanding Subject to Non-Employee Director Deferral Election (in shares)				43,554
Percentage of stock units vested at date of grant (as a percent)				100.00%
Fully Vested Shares Outstanding Subject to Deferral Election by Executive Officers or Other Officers (in shares)			469,165
Total unrecognized compensation cost	$ 3.2	$ 15.5			$ 3.5
Period of recognition of unrecognized compensation cost (in years)	4.0	4.0			2.8
Granted (in shares)		143,601			59,738	[1]	59,738
Number of years of service to be completed to participate in the program (in years)					3 years
Minimum interest coverage ratio, numerator					2.5
Minimum interest coverage ratio, denominator					1.0
Vesting period (in years)	4 years				3 years
Fair value assumptions used in market-based portion of performance shares valuation model (Monte Carlo model)
Number of simulations					100,000
Expected volatility (as a percent)	50.00%				50.00%
Risk-free interest rate (as a percent)	0.95%				0.42%

[1] Reflects the maximum number of performance shares that can be issued.