Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash paid during the period for:
Interest	$ 108,422	$ 96,958	$ 98,754
Income taxes	46,811	52,040	16,610
Non-cash investing and financing activities:
Issuance of stock dividend	609	584	520
Non-controlling interest	0	0	2,733
Debt retired in conversion to stock	0	25,000	132,530
Embedded derivative, net retired in conversion to stock	$ 0	$ 889	$ 6,680