Equity Investees (Schedule of Operations for Equity Investees) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
INCOME STATEMENT DATA:
Revenues	$ 27,768	$ 30,597	$ 83,962	$ 88,003
Operating income	17,772	22,334	57,444	63,159
Net income	$ 15,721	$ 20,739	$ 51,731	$ 58,754

The amount of net income (loss) reported by an equity method investment of the entity.

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