Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Noncash investing and financing activity
Capital projects incurred but not yet paid	$ 10,708	$ 5,502
Purchase of a productive asset through seller-financing	1,010	5,055
Shares issued for acquisition of business	4,303	0
Dividends declared not yet paid	$ 3,967	$ 3,127