Statement of Cash Flows - Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash paid during the year for:
Interest	$ 61,889	$ 57,717	$ 54,843
Income taxes	$ 1,622	$ 1,166	$ 1,119