Supplemental Cash Flow Information (Schedule of Cash, Cash Equivalents and Restricted Cash Adjustments) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Net changes in operating assets and liabilities	$ 52,390	$ 57,626
Net cash provided by (used in) operating activities	114,705	148,112
Effect of changes in foreign currency rates on cash	10,310	8,593
Increase (decrease) in cash	(390,595)	69,426
Cash and cash equivalents	254,103	166,501	$ 207,867
Total cash, cash equivalents and restricted cash	$ 367,494	362,672	$ 758,089	$ 293,246
As Reported [Member]
Net changes in operating assets and liabilities		(52,931)
Net cash provided by (used in) operating activities		37,555
Effect of changes in foreign currency rates on cash		6,077
Increase (decrease) in cash		$ (43,647)