Other Investments (Summarized Investee Financial Information) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Balance Sheets
Total assets	$ 2,118,045	$ 2,493,798
Total liabilities	1,016,502	1,169,125
Noncontrolling interests	2,007	13,258
Total equity attributable to parent entities	1,099,536	1,311,415
Income Statements
Revenues	262,970	261,867	$ 272,281
Expenses	(187,257)	(167,999)	(227,720)
Net income attributable to parent entities	$ 75,056	$ 91,633	$ 42,209