Equity Investees (Schedule of Operations for Equity Investees) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
INCOME STATEMENT DATA:
Revenues	$ 209,674	$ 180,056	$ 191,078
Operating Income	155,920	129,160	139,604
Net Income	$ 139,436	$ 115,669	$ 134,479