Supplemental cash flow information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash paid during the period for:
Interest	$ 13,980	$ 15,775
Income taxes, net of refunds	8,810	9,115
Capital expenditures incurred but not yet paid	$ (103)	$ 29