Financing Agreements - Schedule of Long-term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2018	Jan. 23, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt	$ 3,460		$ 3,460
Less: Current portion of long-term debt	1		337
Total long-term debt, excluding current portion	$ 3,459		$ 3,123
Debentures \| 7.25% Voya Holdings Inc. debentures, due 2023
Debt Instrument [Line Items]
Annual interest rate on debt	7.25%		7.25%
Long-term debt	$ 144		$ 143
Debentures \| 7.63% Voya Holdings Inc. debentures, due 2026
Debt Instrument [Line Items]
Annual interest rate on debt	7.63%		7.63%
Long-term debt	$ 176		$ 186
Debentures \| 6.97% Voya Holdings Inc. debentures, due 2036
Debt Instrument [Line Items]
Annual interest rate on debt	6.97%		6.97%
Long-term debt	$ 94		$ 94
Notes payable, other \| 8.42% Equitable of Iowa Companies Capital Trust II Notes, due 2027
Debt Instrument [Line Items]
Annual interest rate on debt	8.42%		8.42%
Long-term debt	$ 14		$ 14
Loans payable \| 1.00% Windsor Property Loan
Debt Instrument [Line Items]
Annual interest rate on debt	1.00%		1.00%
Long-term debt	$ 5		$ 5
Senior Notes \| 5.5% Senior Notes, due 2022
Debt Instrument [Line Items]
Annual interest rate on debt	5.50%		5.50%
Long-term debt	$ 361		$ 361
Senior Notes \| 2.9% Senior Notes, due 2018
Debt Instrument [Line Items]
Annual interest rate on debt			2.90%
Long-term debt	$ 0		$ 337
Senior Notes \| 5.7% Senior Notes, due 2043
Debt Instrument [Line Items]
Annual interest rate on debt	5.70%		5.70%
Long-term debt	$ 395		$ 395
Senior Notes \| 3.65% Senior Notes, due 2026
Debt Instrument [Line Items]
Annual interest rate on debt	3.65%		3.65%
Long-term debt	$ 495		$ 495
Senior Notes \| 4.8% Senior Notes, due 2046
Debt Instrument [Line Items]
Annual interest rate on debt	4.80%		4.80%
Long-term debt	$ 297		$ 296
Senior Notes \| 3.125% Senior Notes, due 2024
Debt Instrument [Line Items]
Annual interest rate on debt	3.125%		3.125%
Long-term debt	$ 396		$ 396
Junior Subordinated Notes \| 5.65% Fixed-to-Floating Rate Junior Subordinated Notes, due 2053
Debt Instrument [Line Items]
Annual interest rate on debt	5.65%		5.65%
Long-term debt	$ 739		$ 738
Junior Subordinated Notes \| 4.7% Fixed-to-Floating Rate Junior Subordinated Notes, due 2048
Debt Instrument [Line Items]
Annual interest rate on debt	4.70%	4.70%
Long-term debt	$ 344		$ 0

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

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(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. 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 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: 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 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))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. 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 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. 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 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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