Consolidated Investment Entities (Fair Value Measurement) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2013	Dec. 31, 2012
Variable Interest Entity [Line Items]
Revolving lines of credit	$ 9,363.9
Outstanding borrowings	7,389.1
VOEs
Variable Interest Entity [Line Items]
Period of funds fully redeemed, period	90 days
Number of limited partnerships	35
VOEs \| Private Equity Funds
Variable Interest Entity [Line Items]
Revolving lines of credit	400.0	325.3
Asset coverage, percentage	350.00%
Outstanding borrowings	314.2	288.4
VOEs \| LIBOR \| Private Equity Funds
Variable Interest Entity [Line Items]
Description of variable rate basis	LIBOR
Basis spread	2.35%
VOEs \| EURIBOR \| Private Equity Funds
Variable Interest Entity [Line Items]
Description of variable rate basis	EURIBOR
Basis spread	2.50%
VIEs \| Corporate Loans \| Senior Secured Corporate Loans
Variable Interest Entity [Line Items]
Fair value exceeds unpaid principal	14.8
Unpaid principal exceeds fair value, amount		26.9
Default of collateral assets, percentage	1.00%	1.00%
VIEs \| Corporate Loans \| Senior Secured Corporate Loans \| LIBOR or Prime
Variable Interest Entity [Line Items]
Basis spread	10.00%
VIEs \| Corporate Loans \| Senior Secured Corporate Loans \| LIBOR
Variable Interest Entity [Line Items]
Description of variable rate basis	LIBOR
VIEs \| Corporate Loans \| Senior Secured Corporate Loans \| PRIME
Variable Interest Entity [Line Items]
Description of variable rate basis	PRIME
VIEs \| Collateralized Debt Obligations \| Senior Secured Floating Rate Leveraged Loans
Variable Interest Entity [Line Items]
Unpaid principal exceeds fair value, amount	$ 140.0	$ 99.6
Weighted average maturity	9 years
VIEs \| Collateralized Debt Obligations \| Senior Secured Floating Rate Leveraged Loans \| LIBOR
Variable Interest Entity [Line Items]
Description of variable rate basis	LIBOR
VIEs \| Collateralized Debt Obligations \| Senior Secured Floating Rate Leveraged Loans \| LIBOR \| Minimum
Variable Interest Entity [Line Items]
Basis spread	0.22%
VIEs \| Collateralized Debt Obligations \| Senior Secured Floating Rate Leveraged Loans \| LIBOR \| Maximum
Variable Interest Entity [Line Items]
Basis spread	7.00%

Default of Collateral Assets, Percentage

No definition available.

Name:	ingus_DefaultofCollateralAssetsPercentage
Namespace Prefix:	ingus_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Fair Value Exceeds Unpaid Principal, Corporate Loan

+ References

No definition available.

+ Details

Name:	ingus_FairValueExceedsUnpaidPrincipalCorporateLoan
Namespace Prefix:	ingus_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line of Credit Facility, Asset Coverage, Percentage

+ References

No definition available.

+ Details

Name:	ingus_LineOfCreditFacilityAssetCoveragePercentage
Namespace Prefix:	ingus_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of Limited Partnerships

+ References

No definition available.

+ Details

Name:	ingus_NumberOfLimitedPartnerships
Namespace Prefix:	ingus_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Period of Funds Fully Redeemed, Period

+ References

No definition available.

+ Details

Name:	ingus_PeriodOfFundsFullyRedeemedPeriod
Namespace Prefix:	ingus_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Unpaid Principal Exceeds Fair Value, Corporate Loan

+ References

No definition available.

+ Details

Name:	ingus_UnpaidPrincipalExceedsFairValueCorporateLoan
Namespace Prefix:	ingus_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Weighted Average Maturity, Debt

+ References

No definition available.

+ Details

Name:	ingus_WeightedAverageMaturityDebt
Namespace Prefix:	ingus_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- 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

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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

- Definition

Amount borrowed under the credit facility as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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

- 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

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 210.5-02.19(b),22(b))

-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 19, 22

-Article 5

+ Details

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

- Definition

The percentage points (also referred to as 'margin') added to the reference rate as stated in the loan agreement and used to compute the variable rate on the loans receivable. For instance, the loan agreement might state that the interest rate the borrower is obligated to pay is the London Interbank Offered Rate (LIBOR) plus three quarters (3/4) of a percentage point adjusted quarterly (each three months). LIBOR in this example is the index or reference rate, 3/4 percentage point is the margin, the reference rate plus the margin is the fully indexed rate. This element would be used to report separately the margin.

+ References

No definition available.

+ Details

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

- Definition

The reference rate for the variable rate of the loans receivable, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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

- Details

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