Debt (Details 2) - Notes Payable (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Notes Payable
Total amount financed under arrangements with vendors	$ 2.0
Notes Payable, Vendors
Notes Payable
Latest date the outstanding notes are required to be repaid	Jul. 31, 2015
Minimum stated interest rate	0.00%
Maximum stated interest rate	1.70%
Weighted-average effective interest rate	5.30%