Investments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Marketable Securities [Abstract]
Marketable Securities Cost	$ 43.4	$ 43.2
Marketable Securities Carrying Value	45.9	45.5
Marketable Securities Unrealized Gain	2.5	2.3
Schedule of Available for Sale Contractual Maturities Amortized Cost [Abstract]
Amortized Cost Due within 1 year	10.0
Amortized Cost After 1 year but within 5 years	18.4
Amortized Cost After 5 years but within 10 years	9.6
Amortized Cost Due after 10 years	0
Schedule of Available for Sale Contractual Maturities Fair Value [Abstract]
Fair Value Due within 1 year	10.1
Fair Value After 1 year but within 5 years	18.9
Fair Value After 5 years but within 10 years	9.6
Fair Value Due after 10 years	0
Schedule of Available For Sale Investments [Line Items]
Amortized Cost	38.0	38.5
Gross Unrealized Gain	0.6	1.2
Gross Unrealized Loss	0	0
Available for Sale	38.6	39.7
Carrying Value	38.6	39.7
Schedule of Trading Investments [Line Items]
Trading Security Amortized Cost	5.4	4.7
Trading Security Gross Unrealized Gain	1.9	1.1
Trading Security Gross Unrealized Loss	0	0
Trading Security Fair Value	7.3	5.8
Trading Security Carrying Value	$ 7.3	$ 5.8