Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Supplemental cash flow information
Interest paid	$ 110,141	$ 110,192
Income taxes paid	13,635	9,878
Changes in accounts payable related to purchases of revenue earning equipment	18,307	3,902
Operating and revenue earning equipment acquired under capital leases	$ 5,956	$ 3,788