Goodwill and Other Intangible Assets Expected future amortization expense (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated annual amortization expense, year one	$ 1.2
Estimated annual amortization expense, year two	1.2
Estimated annual amortization expense, year three	1.2
Estimated annual amortization expense, year four	1.2
Estimated annual amortization expense, year five	1.2
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated annual amortization expense, year one	1.6
Estimated annual amortization expense, year two	1.6
Estimated annual amortization expense, year three	1.6
Estimated annual amortization expense, year four	1.6
Estimated annual amortization expense, year five	$ 1.6