Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Supplemental Cash Flow Information [Abstract]
Interest paid	$ 20,356	$ 18,008
Noncash investing and financing activity
Capital projects incurred but not yet paid	6,319	13,104
Investment merger (decreasing equity method investments and non-controlling interest)	8,360	0
Dividends declared not yet paid	$ 4,501	$ 4,342