Subsequent Events (Details) (USD $)	3 Months Ended	9 Months Ended	0 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Oct. 25, 2013 Subsequent event	Oct. 02, 2013 Subsequent event KVS Transportation, Inc. item	Oct. 31, 2013 Subsequent event Peak
Subsequent event
Total consideration				$ 154,500,000
Amount payable in future annual installments to acquire business				66,800,000
Number of future annual installments				3
Dividend declared (in dollars per share)	$ 0.04		$ 0.04
Cash proceeds from sale of businesses in Alaska		$ 10,000,000			$ 135,500,000