Financing Activity - Carrying and Fair Values of Mortgage Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Mortgage loans, carrying value	$ 904,641	$ 1,047,906
Secured Debt
Debt Instrument [Line Items]
Debt issuance costs, line of credit arrangements	2,000	3,100
Carrying Value
Debt Instrument [Line Items]
Mortgage loans, carrying value	904,600	1,047,900
Fair Value
Debt Instrument [Line Items]
Mortgage loans, fair value	$ 890,100	$ 1,002,300

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount, after accumulated amortization, of debt issuance costs related to line of credit arrangements. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section S45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=68176171&loc=SL68176184-208336

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Fair value portion of contractual obligation to pay money on demand or on fixed or determinable dates.

+ References

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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
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