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Stock-Based Compensation Plans and Employee Benefits (Stock-based Compensation) (Details) (USD $) | 12 Months Ended | 1 Months Ended |
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Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Jan. 31, 2014 | Feb. 28, 2013 | Jan. 10, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Stock-based compensation expense | $ 13,314,000us-gaap_AllocatedShareBasedCompensationExpense | $ 19,261,000us-gaap_AllocatedShareBasedCompensationExpense | $ 15,293,000us-gaap_AllocatedShareBasedCompensationExpense |  |  |
Unrecognized compensation cost | 2,200,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized |  |  |  |  |
Weighted-average period to recognize the unrecognized compensation cost | 1 year 5 months 1 day |  |  |  |  |
Deferred compensation share-based arrangements, liability, current and noncurrent | 8,700,000us-gaap_DeferredCompensationSharebasedArrangementsLiabilityCurrentAndNoncurrent |  |  |  |  |
2013 Performance Incentive Plan |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Number of Points Issued | 83star_NumberofPointsIssued / us-gaap_AwardTypeAxis = star_A2013PerformanceIncentivePlanMember |  |  |  |  |
Restricted stock units |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value | 39,200,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember | 31,600,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember | 29,100,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] |  |  |  |  |  |
Number of Shares, Non-vested at December 31, 2013 | 2,779,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |  | 2,779,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |
Granted, Number of Shares | 306,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |  |  |  |
Vested, Number of Shares | (2,757,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |  |  |  |
Forfeited, Number of Shares | (8,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |  |  |  |
Number of Shares, Non-vested at December 31, 2014 | 320,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember | 2,779,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] |  |  |  |  |  |
Weighted Average Grant Date Fair Value Per Share,Non-vested at December 31, 2013 | $ 5.85us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |  | 5.85us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |
Granted, Weighted Average Grant Date Fair Value Per Share | $ 15.31us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |  |  |  |
Vested, Weighted Average Grant Date Fair Value Per Share | $ 6.09us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |  |  |  |
Forfeited, Weighted Average Grant Date Fair Value Per Share | $ 15.69us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |  |  |  |
Weighted Average Grant Date Fair Value Per Share,Non-vested at December 31, 2014 | $ 12.57us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember | $ 5.85us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |  |  |
Non-vested at December 31, 2013, Aggregate Intrinsic Value | 39,659,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueNonvested / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |  | 39,659,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueNonvested / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |
Non-vested at December 31, 2014, Aggregate Intrinsic Value | 4,367,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueNonvested / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember | 39,659,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueNonvested / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember |  |  |  |
Long-term Incentive Plan 2009 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized | 8,000,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized / us-gaap_PlanNameAxis = star_LongTermIncentivePlan2009Member |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award Additional Number of Shares that Can be Authorized | 500,000star_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalNumberOfSharesThatCanBeAuthorized / us-gaap_PlanNameAxis = star_LongTermIncentivePlan2009Member |  |  |  |  |
Long-term Incentive Plan 2006 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized | 4,550,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized / us-gaap_PlanNameAxis = star_LongTermIncentivePlan2006Member |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Reserved for Grants of Options | 1,000,000star_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesReservedForGrantsOfOptions / us-gaap_PlanNameAxis = star_LongTermIncentivePlan2006Member |  |  |  |  |
Long-term Incentive Plan 2006 and 2009 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |
Shares available for issuance | 4,000,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_PlanNameAxis = star_LongTermIncentivePlan2006And2009Member |  |  |  |  |
Employees | Restricted stock units |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] |  |  |  |  |  |
Vested, Number of Shares | (2,757,427)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] |  |  |  |  |  |
Restricted shares awarded | 1,369,809us-gaap_RestrictedStockSharesIssuedNetOfSharesForTaxWithholdings / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockUnitsRSUMember / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |  |  |  |
Employees | Amended restricted stock units vesting on January 1, 2014 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] |  |  |  |  |  |
Vested, Number of Shares | (1,696,053)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_AwardTypeAxis = star_RestrictedStockUnitsAmendedUnitsVestingonJanuary12014Member / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |  |  |  |
Employees | Service-based restricted stock units vesting on March 2014 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] |  |  |  |  |  |
Vested, Number of Shares | (80,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_AwardTypeAxis = star_ServicebasedRestrictedStockUnitsVestingonMarch2014Member / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |  |  |  |
Employees | Common Stock Subject to Sales Restriction |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] |  |  |  |  |  |
Vested, Number of Shares |  |  |  | (235,414)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_AwardTypeAxis = star_CommonStockSubjecttoSalesRestrictionMember / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] |  |  |  |  |  |
Weighted Average Grant Date Fair Value Per Share,Non-vested at December 31, 2014 | $ 14.89us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = star_CommonStockSubjecttoSalesRestrictionMember / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |  |  |  |
Non-vested at December 31, 2014, Aggregate Intrinsic Value | $ 3,500,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueNonvested / us-gaap_AwardTypeAxis = star_CommonStockSubjecttoSalesRestrictionMember / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |  |  |  |
Restricted shares awarded | 132,653us-gaap_RestrictedStockSharesIssuedNetOfSharesForTaxWithholdings / us-gaap_AwardTypeAxis = star_CommonStockSubjecttoSalesRestrictionMember / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |  |  |  |
Employees | Common Stock |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] |  |  |  |  |  |
Sale restriction period |  |  |  | 2 years |  |
Employees | Service-based restricted stock units |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] |  |  |  |  |  |
Number of Shares, Non-vested at December 31, 2014 | 64,552us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = star_ServiceBasedRestrictedStockUnitsMember / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] |  |  |  |  |  |
Granted units |  |  |  |  |  | 67,637star_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsGrantedNumber / us-gaap_AwardTypeAxis = star_ServiceBasedRestrictedStockUnitsMember / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember
Employees | Performance-based restricted stock units vesting on December 31, 2016 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] |  |  |  |  |  |
Number of Shares, Non-vested at December 31, 2014 | 50,116us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = star_PerformanceBasedRestrictedStockUnitsVestingonDecember312016Member / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] |  |  |  |  |  |
Granted units |  |  |  |  |  | 51,726star_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsGrantedNumber / us-gaap_AwardTypeAxis = star_PerformanceBasedRestrictedStockUnitsVestingonDecember312016Member / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember
Risk-free interest rate |  |  |  | 0.76%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate / us-gaap_AwardTypeAxis = star_PerformanceBasedRestrictedStockUnitsVestingonDecember312016Member / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |
Expected stock price volatility |  |  |  | 44.84%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate / us-gaap_AwardTypeAxis = star_PerformanceBasedRestrictedStockUnitsVestingonDecember312016Member / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |
Employees | Performance-based restricted stock units vesting on December 31, 2016 | Minimum |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] |  |  |  |  |  |
Vesting percentage |  |  |  | 0.00%star_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestingPercentage / us-gaap_AwardTypeAxis = star_PerformanceBasedRestrictedStockUnitsVestingonDecember312016Member / us-gaap_RangeAxis = us-gaap_MinimumMember / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |
Employees | Performance-based restricted stock units vesting on December 31, 2016 | Maximum |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] |  |  |  |  |  |
Vesting percentage |  |  |  | 200.00%star_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestingPercentage / us-gaap_AwardTypeAxis = star_PerformanceBasedRestrictedStockUnitsVestingonDecember312016Member / us-gaap_RangeAxis = us-gaap_MaximumMember / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |
Employees | Service-based restricted stock units vesting on February 1, 2016 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] |  |  |  |  |  |
Number of Shares, Non-vested at December 31, 2014 | 194,582us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = star_ServicebasedRestrictedStockUnitsVestingonFebruary12016Member / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] |  |  |  |  |  |
Vesting term |  |  |  |  | 3 years |
Employees | Performance based restricted stock units vesting on December 31, 2014 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] |  |  |  |  |  |
Vested, Number of Shares | (381,374)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_AwardTypeAxis = star_PerformanceBasedRestrictedStockUnitsVestingOnDecember312014Member / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |  |  |  |
Employees | Performance-based restricted stock units |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] |  |  |  |  |  |
Vesting percentage | 195.50%star_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestingPercentage / us-gaap_AwardTypeAxis = star_PerformanceBasedRestrictedStockUnitsMember / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |  |  |  |
Employees | Performance-based restricted stock units | Minimum |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] |  |  |  |  |  |
Vesting percentage |  |  |  |  | 0.00%star_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestingPercentage / us-gaap_AwardTypeAxis = star_PerformanceBasedRestrictedStockUnitsMember / us-gaap_RangeAxis = us-gaap_MinimumMember / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |
Employees | Performance-based restricted stock units | Maximum |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] |  |  |  |  |  |
Vesting percentage |  |  |  |  | 200.00%star_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestingPercentage / us-gaap_AwardTypeAxis = star_PerformanceBasedRestrictedStockUnitsMember / us-gaap_RangeAxis = us-gaap_MaximumMember / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |
Employees | Service based restricted stock units with specified vesting dates |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] |  |  |  |  |  |
Number of Shares, Non-vested at December 31, 2014 | 10,666us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = star_ServiceBasedRestrictedStockUnitsWithSpecifiedVestingTermsMember / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember |  |  |  |  |
Employees | Service based restricted stock units with specified vesting dates | Minimum |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] |  |  |  |  |  |
Vesting term | 3 years |  |  |  |  |
Company's chairman and chief executive officer | Service-based restricted stock units vesting on June 15, 2014 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] |  |  |  |  |  |
Vested, Number of Shares | (600,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_AwardTypeAxis = star_ServicebasedRestrictedStockUnitsVestingonJune152014Member / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_BoardOfDirectorsChairmanAndChiefExecutiveOfficerMember |  |  |  |  |
Original Awards [Member] | Employees | Performance based restricted stock units vesting on December 31, 2014 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] |  |  |  |  |  |
Vested, Number of Shares | (195,076)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_AwardTypeAxis = star_PerformanceBasedRestrictedStockUnitsVestingOnDecember312014Member / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember / us-gaap_VestingAxis = star_OriginalAwardsMember |  |  |  |  |
Additional Awards [Member] | Employees | Performance based restricted stock units vesting on December 31, 2014 |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] |  |  |  |  |  |
Vested, Number of Shares | (186,298)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_AwardTypeAxis = star_PerformanceBasedRestrictedStockUnitsVestingOnDecember312014Member / star_ScheduleOfShareBasedCompensationArrangementByTitleOfIndividualAxis = star_EmployeesMember / us-gaap_VestingAxis = star_AdditionalAwardsMember |  |  |  |  |

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- Definition Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 14.F) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section F + Details
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- Definition Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of restricted shares issued as compensation, net of shares for the payment of withholding taxes. This element is to be used only if shares are used in lieu of cash to satisfy all or a portion of withholding taxes. + References No definition available. + Details
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- Definition Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Intrinsic value of equity-based compensation awards not vested. Excludes stock and unit options. + References No definition available. + Details
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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iv) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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