Employee Benefit Plans (Details 13) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Assets Category:
Fair value of pension plan assets	$ 242.5	$ 244.6
NAV [Member]
Assets Category:
Fair value of pension plan assets	238.9	238.9
Commingled pools / Collective Trusts [Member] | U.S. equity [Member]
Assets Category:
Fair value of pension plan assets	33.4	33.7
Commingled pools / Collective Trusts [Member] | International equity [Member]
Assets Category:
Fair value of pension plan assets	48.3	53.8
Redemption Frequency (if currently eligible)	Monthly	Monthly
Redemption Notice Period	10-15 days	10-15 days
Commingled pools / Collective Trusts [Member] | Fixed income [Member]
Assets Category:
Fair value of pension plan assets	81.9	74.0
Redemption Frequency (if currently eligible)	Quaterly	Quaterly
Redemption Notice Period	15 days	15 days
Mutual funds [Member] | U.S. equity [Member]
Assets Category:
Fair value of pension plan assets	38.8	38.2
Mutual funds [Member] | International equity [Member]
Assets Category:
Fair value of pension plan assets	4.4	6.5
Mutual funds [Member] | Fixed income [Member]
Assets Category:
Fair value of pension plan assets	6.9	6.2
Balanced pension trust [Member] | U.S. equity [Member]
Assets Category:
Fair value of pension plan assets	2.1	2.1
Redemption Frequency (if currently eligible)	Daily	Daily
Redemption Notice Period	5 days	5 days
Balanced pension trust [Member] | International equity [Member]
Assets Category:
Fair value of pension plan assets	6.5	7.4
Redemption Frequency (if currently eligible)	Daily	Daily
Redemption Notice Period	5 days	5 days
Balanced pension trust [Member] | Bonds [Member]
Assets Category:
Fair value of pension plan assets	4.4	5.3
Redemption Frequency (if currently eligible)	Daily	Daily
Redemption Notice Period	5 days	5 days
Pension fund [Member] | U.S. equity [Member]
Assets Category:
Fair value of pension plan assets	1.1	1.1
Redemption Frequency (if currently eligible)	Daily	Daily
Redemption Notice Period	7 days	7 days
Pension fund [Member] | International equity [Member]
Assets Category:
Fair value of pension plan assets	5.5	5.7
Redemption Frequency (if currently eligible)	Daily	Daily
Redemption Notice Period	7 days	7 days
Pension fund [Member] | Fixed income [Member]
Assets Category:
Fair value of pension plan assets	4.8	4.1
Redemption Frequency (if currently eligible)	Daily	Daily
Redemption Notice Period	7 days	7 days
Pension fund [Member] | Money market instruments [Member]
Assets Category:
Fair value of pension plan assets	$ 0.7	$ 0.8
Redemption Frequency (if currently eligible)	Daily	Daily
Redemption Notice Period	7 days	7 days