Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Supplemental Cash Flow Information [Line Items]
Interest paid	$ 260,255	$ 217,783
Income taxes paid	10,372	10,186
Increase (decrease) in accounts payable for purchases of property and equipment	(7,825)	(10,197)
Purchase of property and equipment under capital leases and installment purchases	$ 17,933	$ 25,444