Tax Credit Transactions (Textual) (Details) $ in Thousands		1 Months Ended	12 Months Ended
	Dec. 30, 2008 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Aug. 27, 2010 USD ($)	Nov. 17, 2008 ft²
Tax Credit Carryforward [Line Items]
Tax credit transaction income			$ (19,955)	$ (11,853)	$ (11,853)
Deferred Costs			$ 101,419	101,261
Historic Tax Credit Transaction [Member]
Tax Credit Carryforward [Line Items]
Area Of IRS Campus Building | ft²							862,692
Percentage of building leased to IRS							100.00%
Purchase price for non-controlling interest obligation put option		$ 3,200
Rate of return on non-controlling interest		2.00%	2.00%
Percentage of tax credit recapture		20.00%
Tax credit transaction income		$ 11,900
Other income (expense)		(500)
Contribution allocated in non controlling interest				3,000
Recognition of cash received as revenue net of allocated expenses on or after September 2011, period			over the five year credit recapture period as defined in the Internal Revenue Code
Recognition of cash received as revenue net of allocated expenses on or after September 2011, period in years			5 years
Accretion of non-controlling interest liability			$ 1,100	1,100	$ 1,100
Historic Tax Credit Transaction [Member] | Other Liabilities [Member]
Tax Credit Carryforward [Line Items]
Preferred return		$ 1,000
Historic Tax Credit Transaction [Member] | Other Assets [Member]
Tax Credit Carryforward [Line Items]
Deferred Costs			0	500
Historic Tax Credit Transaction [Member] | U S B [Member]
Tax Credit Carryforward [Line Items]
Agreed contribution in project cost						$ 64,100
USB contributions			$ 0	15,100
New Markets Tax Credit Transaction [Member]
Tax Credit Carryforward [Line Items]
Percentage of tax credit recapture			100.00%
Tax credit transaction income	$ 8,000		$ 8,100
Recognition of cash received as revenue net of allocated expenses on or after September 2011, period in years			7 years
Percentage of qualified investments	39.00%
New Markets Tax Credit Transaction [Member] | Other Assets [Member]
Tax Credit Carryforward [Line Items]
Deferred Costs			$ 0	5,300
New Markets Tax Credit Transaction [Member] | U S B [Member]
Tax Credit Carryforward [Line Items]
USB contributions			$ 13,300	$ 13,000