Goodwill and Intangible Assets (Details 4) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Goodwill and Intangible Assets
Total amortization expenses for intangible assets	$ 0.1	$ 0.5	$ 0.2	$ 0.9
Estimated amortization expenses for intangible assets
Remainder of 2014	0.1		0.1
2015	0.3		0.3
2016	0.3		0.3
2017	0.3		0.3
2018	0.3		0.3
Thereafter	$ 0.4		$ 0.4