Investment And Other Gains Investment And Other Gains (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Marketable Securities, Realized Gain (Loss)	$ 0	$ 0	$ 10,038	$ 23,498
Proceeds from sales of marketable securities			18,182	$ 56,449
Marketable securities	0		0		$ 11,745
Available-for-sale Securities, Amortized Cost Basis	$ 1,680		1,680
2017 Sales Transaction [Member]
Proceeds from sales of marketable securities			11,718
2016 Sales Transaction [Member]
Proceeds from sales of marketable securities			$ 6,464