Fair Value of Financial Instruments Carrying Amount and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
Secured Debt | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured notes payable	$ 812,811	$ 952,174
Secured Debt | Estimate of Fair Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured notes payable	850,475	990,296
Term Loan | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured notes payable	100,000	0
Term Loan | Estimate of Fair Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured notes payable	100,000	0
Line of Credit | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured notes payable	0	93,000
Line of Credit | Estimate of Fair Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured notes payable	0	93,000
Senior Notes, Series A | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured notes payable	150,000	0
Senior Notes, Series A | Estimate of Fair Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured notes payable	$ 154,560	$ 0