Amount of unamortized debt discount (premium) and debt issuance costs.

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Amount, after accumulated amortization, of debt discount (premium).

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The charge against earnings in the period to reduce the carrying amount of real property to fair value.

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Fair Value Measurements - Narratives (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) property	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unamortized discount	$ 15,786
Impairment charges	4,790	$ 0
Fair value of impaired real estate	$ 3,900
Impaired properties
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Number of real estate properties \| property	2
Impairment charges	$ 4,800
Bankrupt tenants property
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Number of real estate properties \| property	1
Impairment charges	$ 3,800
Fair value of impaired real estate	3,900
Vacant Property
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Impairment charges	1,000
Unsecured senior notes
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unamortized discount	13,800		$ 9,900
Level 2 \| Carrying Value \| Unsecured senior notes
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unamortized debt issuance cost	18,500		14,700
Unamortized discount	13,800		9,900
Level 3 \| Carrying Value \| Non recourse mortgage
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unamortized debt issuance cost	1,100		1,000
Non-Recourse Debt \| Level 3 \| Carrying Value
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unamortized discount	$ 2,000		$ 1,700