Fair Value Measurement - Summary of interest rate collars (Details) $ in Millions	Sep. 30, 2019 USD ($)
Derivative [Line Items]
Notional Amount	$ 222.3
Collar 1
Derivative [Line Items]
Notional Amount	$ 74.1
LIBOR Ceiling	2.50%
LIBOR Floor	1.20%
Collar 2
Derivative [Line Items]
Notional Amount	$ 74.1
LIBOR Ceiling	2.50%
LIBOR Floor	1.30%
Collar 3
Derivative [Line Items]
Notional Amount	$ 74.1
LIBOR Ceiling	2.50%
LIBOR Floor	1.40%

Cap rate on an interest rate derivative such as an interest rate cap or collar. If market rates exceed the cap rate, a payment or receipt is triggered on the contract.

No definition available.

+ Details

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- Definition

Floor rate on an interest rate derivative such as an interest rate floor or collar. If market rates falls below the floor rate, a payment or receipt is triggered on the contract.

+ References

No definition available.

+ Details

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- Definition

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.

+ References

No definition available.

+ Details

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- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

+ Details

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- Details

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- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=sp_Collar2Member
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- Details

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