Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Supplemental disclosure:
Income taxes paid	$ 6,321	$ 7,864	$ 17,167	$ 18,397
Non-cash investing and financing activities:
Non-cash capital expenditures	$ (17)	$ (149)	$ (190)	$ 115