Financing Agreements - Narrative (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Mar. 17, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Feb. 11, 2015	Dec. 31, 2014	Feb. 14, 2014	Jan. 24, 2014
Debt Instrument [Line Items]
Period of put option agreement	10 years
Put option agreement, face amount	$ 500.0
Period delinquent payment must be cured to avoid put option	30 days
Minimum equity required to main per debt covenant	$ 3,000.0
Loss related to early extinguishment of debt		$ (9.9)	$ 0.0	$ (9.9)	$ 0.0
Outstanding par amount of guaranteed debentures		475.5		475.5			$ 506.1
Revolving lines of credit capacity		8,041.7		8,041.7
Outstanding borrowings		4,750.0		4,750.0
Payments of financing costs		24.4	$ 28.1	49.7	$ 57.4
Unsecured and Uncommitted
Debt Instrument [Line Items]
Revolving lines of credit capacity		1.7		1.7
Outstanding borrowings		1.7		1.7
Unsecured and Committed
Debt Instrument [Line Items]
Revolving lines of credit capacity		7,835.0		7,835.0
Outstanding borrowings		4,552.6		4,552.6
Secured facilities
Debt Instrument [Line Items]
Revolving lines of credit capacity		205.0		205.0
Outstanding borrowings		195.7		195.7
Letter of Credit
Debt Instrument [Line Items]
Revolving lines of credit capacity		175.0		175.0					$ 150.0
Voya Holdings Debentures | Aetna Notes
Debt Instrument [Line Items]
Minimum principal outstanding, 2015		400.0		400.0
Minimum principal outstanding, 2016		300.0		300.0
Minimum principal outstanding, 2017		200.0		200.0
Minimum principal outstanding, 2018		100.0		100.0
Minimum principal outstanding, 2019		$ 0.0		$ 0.0
Voya Holdings Debentures | Aetna Notes | Minimum
Debt Instrument [Line Items]
Quarterly fee to guarantor of notes if minimum principal balance is not met		0.50%		0.50%
Voya Holdings Debentures | Aetna Notes | Maximum
Debt Instrument [Line Items]
Quarterly fee to guarantor of notes if minimum principal balance is not met		1.25%		1.25%
Commerzbank AG, maturing 2018
Debt Instrument [Line Items]
Amount of collateral for credit facility						$ 212.0
Commerzbank AG, maturing 2018 | Letter of Credit
Debt Instrument [Line Items]
Revolving lines of credit capacity						$ 195.0
Senior Notes
Debt Instrument [Line Items]
Annual interest rate on loan	1.875%
Senior Notes | Pre-capitalizedTrust
Debt Instrument [Line Items]
Annual interest rate on loan	3.976%
Debentures | 7.63% Voya Holdings Inc. Debentures, due 2026
Debt Instrument [Line Items]
Annual interest rate on loan		7.63%		7.63%			7.63%
Outstanding principal amount of debt repurchased		$ 30.6		$ 30.6
Revolving Credit agreement
Debt Instrument [Line Items]
Revolving lines of credit capacity								$ 3,000.0
Outstanding borrowings		0.0		0.0
Outstanding amount on credit facilities		736.0		$ 736.0
Interest Expense [Member] | Debentures | 7.63% Voya Holdings Inc. Debentures, due 2026
Debt Instrument [Line Items]
Loss related to early extinguishment of debt		$ 9.9