Related Party Transactions and Arrangements (Indirect Affiliate Expenses) (Details) (Affiliated Entity [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Related party expenses	$ 203,558,000	$ 0	$ 0
Indirect Affiliate Expenses [Member]
Related Party Transaction [Line Items]
Related party expenses	10,975,000	68,000	0
Audrain Building [Member]
Related Party Transaction [Line Items]
Related party expenses	8,724,000	68,000	0
ANST Office Build-Out [Member]
Related Party Transaction [Line Items]
Related party expenses	462,000	0	0
New York (405 Park) Office [Member]
Related Party Transaction [Line Items]
Related party expenses	1,659,000	0	0
Dresher, PA Office [Member]
Related Party Transaction [Line Items]
Related party expenses	92,000	0	0
North Carolina Office [Member]
Related Party Transaction [Line Items]
Related party expenses	38,000	0	0
Lease Agreement and Termination [Member]
Related Party Transaction [Line Items]
Related party expenses	$ 300,000