Supplemental Cash Flow Information Interest and Taxes Paid(Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Cash Flow Information [Abstract]
Cash paid for interest, net	$ 95,243	$ 66,124	$ 59,437
Cash paid for income taxes	$ 40,923	$ 45,738	$ 44,807