Significant Accounting Policies Supplemental Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Income tax (refunds) payments	$ (6,737)	$ 55	$ 60
Interest Paid, Including Capitalized Interest, Operating and Investing Activities	83,776	76,499	82,692
Capital Expenditures Incurred but Not yet Paid	$ 33,473	$ 21,625	$ 15,848