Converted Term Loan, Term

No definition available.

Name:	star_ConvertedTermLoanTerm
Namespace Prefix:	star_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Margin

+ References

No definition available.

+ Details

Name:	star_DebtInstrumentMargin
Namespace Prefix:	star_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Unamortized Discount (Premium) and Deferred Financing Costs, Net

+ References

No definition available.

+ Details

Name:	star_DebtInstrumentUnamortizedDiscountPremiumandDeferredFinancingCostsNet
Namespace Prefix:	star_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 20
-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 16
-Article 9

+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The price per share of the conversion feature embedded in the debt instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6928298&loc=SL6031898-161870

+ Details

Name:	us-gaap_DebtInstrumentConvertibleConversionPrice1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Conversion Rate
-URI http://asc.fasb.org/extlink&oid=6509012

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(5))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21521-112644

+ Details

Name:	us-gaap_DebtInstrumentConvertibleConversionRatio1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Maximum contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMaximum
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMinimum
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of interest capitalized during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Allowance for Funds Used during Construction
-URI http://asc.fasb.org/extlink&oid=6504829

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

+ Details

Name:	us-gaap_InterestCostsCapitalized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 20, 22
-Article 5

+ Details

Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_SecuredCreditFacilityRevolverDueMarch2018Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_FederalFundsEffectiveSwapRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	star_DebtInstrumentInterestRateCategoryAxis=star_InterestRateCategoryOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	star_DebtInstrumentInterestRateCategoryAxis=star_InterestRateCategoryTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_A2016SeniorSecuredCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_SecuredTermLoansCollateralizedByLoansNetLeaseAssetsDueThrough2026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=star_PropertyOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_SecuredCreditFacilitiesTrancheA2FacilityDueMarch2017Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_SecuredCreditFacilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_UnsecuredNotes5Point875PercentSeniorNotesDueMarch2016Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_UnsecuredNotes3point875PercentSeniorNotesDueJuly2016Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_SeniorConvertibleThreePointZeroPercentNotesDueNovember2016Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_SeniorConvertibleOnePoint50PercentNotesDueNovember2016Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_UnsecuredNotes5Point85PercentSeniorNotesDueMarch2017Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_UnsecuredNotesNinePercentSeniorNotesDueJune2017Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_UnsecuredNotesFourPercentSeniorNotesDueNovember2017Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_UnsecuredNotesSevenPointOneTwoFivePercentSeniorNotesDueFebruary2018Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_UnsecuredNotes4point875PercentSeniorNotesDueJuly2018Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_UnsecuredNotesFivePercentSeniorNotesDueJuly2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_UnsecuredNotesSixPointFivePercentSeniorNotesDueJuly2021Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_UnsecuredSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=star_OtherDebtSecuritiesDueOctober2035Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt Obligations, net (Schedule of Debt) (Details) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 31, 2012	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Mar. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Total debt obligations		$ 3,804,738,000		$ 3,804,738,000			$ 4,150,389,000
Debt discounts and deferred financing costs, net		(34,095,000)		(34,095,000)			(31,566,000)
Total debt obligations, net		3,770,643,000		3,770,643,000			4,118,823,000
Interest costs capitalized		1,400,000	$ 1,200,000	2,800,000	$ 2,600,000
2015 $250 Million Secured Revolving Credit Facility
Debt Instrument [Line Items]
Total debt obligations		50,000,000		50,000,000			250,000,000
Line of credit facility, maximum borrowing capacity		250,000,000.0		$ 250,000,000.0
Converted term loan, term				1 year
2015 $250 Million Secured Revolving Credit Facility \| Federal Funds Effective Swap Rate
Debt Instrument [Line Items]
Variable interest rate, spread				0.50%
2015 $250 Million Secured Revolving Credit Facility \| Minimum \| Interest Rate Category One
Debt Instrument [Line Items]
Debt instrument, margin				1.25%
2015 $250 Million Secured Revolving Credit Facility \| Minimum \| Interest Rate Category Two
Debt Instrument [Line Items]
Debt instrument, margin				2.25%
2015 $250 Million Secured Revolving Credit Facility \| Minimum \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Variable interest rate, spread				1.00%
2015 $250 Million Secured Revolving Credit Facility \| Maximum \| Interest Rate Category One
Debt Instrument [Line Items]
Debt instrument, margin				1.75%
2015 $250 Million Secured Revolving Credit Facility \| Maximum \| Interest Rate Category Two
Debt Instrument [Line Items]
Debt instrument, margin				2.75%
2016 Senior Secured Credit Facility
Debt Instrument [Line Items]
Total debt obligations		450,000,000		$ 450,000,000
Variable interest rate, spread				1.00%
Debt instrument, margin				3.50%
2016 Senior Secured Credit Facility \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Variable interest rate, spread				4.50%
2016 Senior Secured Credit Facility \| Federal Funds Effective Swap Rate
Debt Instrument [Line Items]
Variable interest rate, spread				0.50%
2016 Senior Secured Credit Facility \| Minimum \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Variable interest rate, spread				1.00%
Term loans collateralized by net lease assets
Debt Instrument [Line Items]
Total debt obligations		$ 235,016,000		$ 235,016,000			239,547,000
Stated interest rate, minimum				4.85%
Stated interest rate, maximum				7.26%
Weighted average interest rate		5.20%		5.20%
Term loans collateralized by net lease assets \| London Interbank Offered Rate (LIBOR) \| Property One
Debt Instrument [Line Items]
Variable interest rate, spread				2.00%
2012 Secured Tranche A-2 Facility
Debt Instrument [Line Items]
Total debt obligations		$ 0		$ 0			339,717,000
Variable interest rate, spread	5.75%
2012 Secured Tranche A-2 Facility \| Minimum \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Variable interest rate, spread				1.25%
Total secured credit facilities and term loans
Debt Instrument [Line Items]
Total debt obligations		735,016,000		$ 735,016,000			829,264,000
5.875% senior notes
Debt Instrument [Line Items]
Total debt obligations		$ 0		$ 0			261,403,000
Stated Interest Rates		5.875%		5.875%		5.875%
3.875% senior notes
Debt Instrument [Line Items]
Total debt obligations		$ 0		$ 0			265,000,000
Stated Interest Rates		3.875%		3.875%
3.00% senior convertible notes
Debt Instrument [Line Items]
Total debt obligations		$ 200,000,000		$ 200,000,000			200,000,000
Stated Interest Rates		3.00%		3.00%
Convertible debt conversion ratio				0.085
Convertible debt conversion price		$ 11.77		$ 11.77
1.50% senior convertible notes
Debt Instrument [Line Items]
Total debt obligations		$ 200,000,000		$ 200,000,000			200,000,000
Stated Interest Rates		1.50%		1.50%
Convertible debt conversion ratio				0.0578
Convertible debt conversion price		$ 17.29		$ 17.29
5.85% senior notes
Debt Instrument [Line Items]
Total debt obligations		$ 99,722,000		$ 99,722,000			99,722,000
Stated Interest Rates		5.85%		5.85%
9.00% senior notes
Debt Instrument [Line Items]
Total debt obligations		$ 275,000,000		$ 275,000,000			275,000,000
Stated Interest Rates		9.00%		9.00%
4.00% senior notes
Debt Instrument [Line Items]
Total debt obligations		$ 550,000,000		$ 550,000,000			550,000,000
Stated Interest Rates		4.00%		4.00%
7.125% senior notes
Debt Instrument [Line Items]
Total debt obligations		$ 300,000,000		$ 300,000,000			300,000,000
Stated Interest Rates		7.125%		7.125%
4.875% senior notes
Debt Instrument [Line Items]
Total debt obligations		$ 300,000,000		$ 300,000,000			300,000,000
Stated Interest Rates		4.875%		4.875%
5.00% senior notes
Debt Instrument [Line Items]
Total debt obligations		$ 770,000,000		$ 770,000,000			770,000,000
Stated Interest Rates		5.00%		5.00%
6.50% senior notes
Debt Instrument [Line Items]
Total debt obligations		$ 275,000,000		$ 275,000,000			0
Stated Interest Rates		6.50%		6.50%		6.50%
Unsecured Notes
Debt Instrument [Line Items]
Total debt obligations		$ 2,969,722,000		$ 2,969,722,000			3,221,125,000
Other debt obligations
Debt Instrument [Line Items]
Total debt obligations		$ 100,000,000		$ 100,000,000			$ 100,000,000
Variable interest rate, spread				1.50%