Related Party Transactions and Arrangements (Indirect Affiliate Expenses) (Details) (Detail) (Affiliated Entity [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	$ 43,809	$ 53,221	$ 267,471	$ 328,054
Audrain Building [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	3,517		3,922
ANST Office Build Out [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	335		335
New York Office [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	116		187
Dresher, PA Office [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	17		36
North Carolina Office [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	12		15
Indirect Affiliate Expenses [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	$ 3,997	$ 0	$ 4,495	$ 0