Supplemental Cash Flow Information (Tables)

6 Months Ended

Jun. 30, 2017

Supplemental Cash Flow Information [Abstract]

Supplemental Disclosure of Cash Flow Information and Non-cash Investing and Financing Activities

	Six Months Ended June 30,
	2017			2016
Supplemental disclosure of cash flow information:
Interest paid	$	260,255		$	217,783
Income taxes paid	10,372			10,186
Supplemental disclosure of non-cash investing and financing activities:
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