Other Assets (Schedule of Other Assets) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Equity Method Investments And Other Assets [Abstract]
Accounts receivable and other assets			$ 2,703	$ 9,017
Regulatory deposits			8,208	8,208
Reserves for replacement, insurance and tax escrows			4,110	4,046
Marketable securities			0	11,745
Other Assets	$ 15,021	$ 33,016	$ 15,021	$ 33,016