Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplemental disclosure of cash flow information
Interest paid	$ 19,292	$ 19,944	$ 22,932
Income taxes paid, net of refunds	4,909	36,783	5,332
Noncash investing and financing activity
Capital projects incurred but not yet paid	7,507	6,000	3,870
Purchase of a productive asset through seller-financing	1,010	6,634	14,694
Outstanding payment for acquisition of business	0	0	128
Shares issued for acquisition of business	4,303	31,050	0
Outstanding shares to be issued for acquisition of business	0	4,470	0
Dividends declared not yet paid	$ 4,338	$ 4,059	$ 3,107