Supplemental Disclosures of Cash Flow Information and Noncash Activities (Supplemental Cash Flow Information) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Elements [Abstract]
Cash paid for income taxes, net of refunds received	$ 5,389	$ 11,646	$ 7,362
Cash paid for interest	$ 229,779	$ 204,442	$ 154,527