Related Party Transactions and Arrangements (Asset Management Fees) (Narrative) (Details) - Asset Management Fee [Member] - Advisor [Member]	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2014 USD ($)	Sep. 30, 2015 criteria shares	Sep. 30, 2014 USD ($) shares	Dec. 31, 2013 shares
ARCT IV [Member]
Related Party Transaction [Line Items]
Cumulative, pre-tax, non-compounded return		6.00%
Number of criteria for vesting | criteria		1
Percent used to calculate asset management fees		0.1875%
Calculation of asset management fees, denominator (shares)		1
ARCT IV [Member]
Related Party Transaction [Line Items]
Related party expenses | $	$ 0		$ 13,900,000
ARCT IV [Member] | Member Units [Member]
Related Party Transaction [Line Items]
Stock issued in lieu of cash for management fees, shares			498,857
Exchange ratio to convert Class B Units into OP Units			2.3961
ARCT IV [Member] | Member Units [Member] | ARCT IV [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Stock Approved For Issuance				492,483