Income Taxes (Income Tax Benefit (Expense) Reconciliation) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Federal expense at statutory tax rate		$ 0	$ (70,894)	$ (64,887)
Nontaxable income of NNN		0	69,651	63,353
State taxes, net of federal benefit		0	(141)	(196)
Amortization of built-in gain tax		0	0	372
Expiration of built-in gain tax		0	316	1,792
Other		55	0	(58)
Built-in gain tax liability	[1]	22	(197)	0
TRS Revocation Election	[1]	0	(4,363)	0
Valuation allowance increase	[1]	(77)	(5,047)	(619)
Total expense for income taxes		$ 0	$ (10,675)	$ (243)

[1] The change for the year ended December 31, 2015, is due to TRS Revocation Election.