Summary of Significant Accounting Policies - Deferred Leasing Intangibles Included in Total Assets and Liabilities (Parenthetical) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Total accumulated amortization of deferred leasing intangibles included in total assets	$ 28,808	$ 30,017
Total accumulated amortization of deferred leasing intangibles included in total liabilities	$ 8,735	$ 8,240