Supplemental Cash Flow Information - Supplemental Disclosures to the Consolidated Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Supplemental Cash Flow Elements [Abstract]
Cash paid for interest expense	$ 23,691	$ 21,492
Cash paid for federal income taxes	1,820	$ 257
Non-cash investing and financing activities:
Common stock issued for asset acquisition	5,500
Cost to issue equity included in accounts payable	$ 1,000