Commitments and Contingencies (Details) - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Loss Contingencies [Line Items]
Estimated Litigation Liability	$ 0	$ 0
Letters of Credit Outstanding, Amount	0
Surety Bond [Member]
Loss Contingencies [Line Items]
Outstanding surety bonds	23,000,000	$ 12,200,000
Letter of Credit [Member]
Loss Contingencies [Line Items]
Letter of Credit Facility, Maximum Borrowing Capacity	5,000,000
Optional Facility Increase [Member] | Letter of Credit [Member]
Loss Contingencies [Line Items]
Letter of Credit Facility, Maximum Borrowing Capacity	$ 7,500,000