Benefit Plans (Non-Qualified Retirement Plans) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012
Non-Qualified Retirement Plans [Abstract]
Expected contributions in 2013	8.6
Future expected benefit payments, 2013	8.6
Future expected benefit payments, 2014	7.7
Future expected benefit payments, 2015	6.0
Future expected benefit payments, 2016	5.8
Future expected benefit payments, 2017	6.0
Future expected benefit payments, 2018 through 2022	30.1
Supplemental Executive Retirement Plan and Exess Plan (SERPs)
Non-Qualified Retirement Plans [Abstract]
Non-qualified retirement plan, number of years of highest average annual compensation used to determine benefits	5 years
Non-qualified retirement plan, number of years of employment used to determine benefits	10 years

Non-qualified Retirement Plan, Number of Years of Employment Used to Determine Benefits

No definition available.

Name:	ingli_NonQualifiedRetirementPlanNumberOfYearsOfEmploymentUsedToDetermineBenefits
Namespace Prefix:	ingli_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Non-qualified Retirement Plan, Number of Years of Highest Average Annual Compensation Used to Determine Benefits

+ References

No definition available.

+ Details

Name:	ingli_NonQualifiedRetirementPlanNumberOfYearsOfHighestAverageAnnualCompensationUsedToDetermineBenefits
Namespace Prefix:	ingli_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	ingli_NonQualifiedRetirementPlansAbstract
Namespace Prefix:	ingli_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph g

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsInNextFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of benefits expected to be paid in the five fiscal years after the fifth fiscal year following the latest fiscal year from a defined benefit plan.

+ References

+ Details

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

- Definition

Amount of benefits expected to be paid in the next fiscal year following the latest fiscal year from a defined benefit plan.

+ References

+ Details

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

- Definition

Amount of benefits expected to be paid in the fifth fiscal year following the latest fiscal year from a defined benefit plan.

+ References

+ Details

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

- Definition

Amount of benefits expected to be paid in the fourth fiscal year following the latest fiscal year from a defined benefit plan.

+ References

+ Details

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

- Definition

Amount of benefits expected to be paid in the third fiscal year following the latest fiscal year from a defined benefit plan.

+ References

+ Details

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

- Definition

Amount of benefits expected to be paid in the second fiscal year following the latest fiscal year from a defined benefit plan.

+ References

+ Details

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