Long-term debt Long-Term Debt--Capital Leases (Details) (U.S. Bank National Association, Capital Lease Obligations, USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
U.S. Bank National Association | Capital Lease Obligations
Capital leases
Proceeds from sale leaseback		$ 24,500
Lease term	84 months
Purchase option period	72 months
Implicit interest rate	3.80%
Minimum lease payments	$ 3,181