Supplemental Cash Flow Information (Tables)

12 Months Ended

Dec. 31, 2017

Supplemental Cash Flow Elements [Abstract]

Supplemental Cash Flow Information

	Year ended December 31,
	2017		2016		2015
Amount paid for interest	$	45,472	$	44,063	$	54,763
Amount paid for income taxes, net	42,003		132,695		34,404
Non-cash conversion of convertible notes to common shares	—		43,215		44,310
Accrued capital expenditures	13,824		12,391		5,074