Related Party Transactions and Arrangements (Offering Related Costs) (Details) (Affiliates of Former Manager [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Related party expenses	$ 16,089,000	$ 103,206,000	$ 826,000
Offering Related Costs [Member]
Related Party Transaction [Line Items]
Related party expenses	2,150,000	161,796,000	211,391,000
Commissions And Fees [Member]
Related Party Transaction [Line Items]
Related party expenses	0	148,232,000	184,384,000
Offering Costs And Other Reimbursements [Member]
Related Party Transaction [Line Items]
Related party expenses	$ 2,150,000	$ 13,564,000	$ 27,007,000