Financing Agreements - Credit Facilities (Details) (USD $)	Mar. 31, 2014
Line of Credit Facility [Line Items]
Capacity	$ 9,977,900,000
Utilization	5,599,900,000
Unused Commitment	4,372,700,000
ING Bank
Line of Credit Facility [Line Items]
Capacity	1,275,000,000
Utilization	673,100,000
Unused Commitment	601,900,000
Secured facilities
Line of Credit Facility [Line Items]
Capacity	265,000,000
Utilization	259,700,000
Unused Commitment	0
Secured and Uncommitted | Voya Financial, Inc.
Line of Credit Facility [Line Items]
Capacity	10,000,000
Utilization	4,700,000
Unused Commitment	0
Committed and Conditional | ReliaStar Life Insurance Company
Line of Credit Facility [Line Items]
Capacity	255,000,000
Utilization	255,000,000
Unused Commitment	0
Unsecured and Uncommitted
Line of Credit Facility [Line Items]
Capacity	1,700,000
Utilization	1,700,000
Unused Commitment	0
Unsecured and Uncommitted | Voya Financial, Inc.
Line of Credit Facility [Line Items]
Capacity	1,700,000
Utilization	1,700,000
Unused Commitment	0
Unsecured and Committed
Line of Credit Facility [Line Items]
Capacity	9,711,200,000
Utilization	5,338,500,000
Unused Commitment	4,372,700,000
Unsecured and Committed | Voya Financial, Inc.
Line of Credit Facility [Line Items]
Capacity	3,000,000,000
Utilization	829,900,000
Unused Commitment	2,170,100,000
Unsecured and Committed | Security Life of Denver International Limited
Line of Credit Facility [Line Items]
Capacity	150,000,000
Utilization	147,000,000
Unused Commitment	3,000,000
Unsecured and Committed | Voya Financial, Inc./ Langhorne I, LLC
Line of Credit Facility [Line Items]
Capacity	500,000,000
Utilization	0
Unused Commitment	500,000,000
Unsecured and Committed | Voya Financial, Inc./ Security Life of Denver International Limited
Line of Credit Facility [Line Items]
Capacity	750,000,000
Utilization	750,000,000
Unused Commitment	0
Unsecured and Committed | Security Life of Denver International Limited
Line of Credit Facility [Line Items]
Capacity	1,125,000,000
Utilization	631,600,000
Unused Commitment	493,400,000
Unsecured and Committed | Voya Financial, Inc. / Security Life of Denver International Limited
Line of Credit Facility [Line Items]
Capacity	750,000,000
Utilization	750,000,000
Unused Commitment	0
Unsecured and Committed | Voya Financial, Inc. / Security Life of Denver International Limited
Line of Credit Facility [Line Items]
Capacity	250,000,000
Utilization	250,000,000
Unused Commitment	0
Unsecured and Committed | Voya Financial, Inc. / Security Life of Denver International Limited
Line of Credit Facility [Line Items]
Capacity	475,000,000
Utilization	475,000,000
Unused Commitment	0
Unsecured and Committed | Voya Financial, Inc. / Roaring River II LLC
Line of Credit Facility [Line Items]
Capacity	995,000,000
Utilization	588,000,000
Unused Commitment	407,000,000
Unsecured and Committed | Voya Financial, Inc. / Roaring River III LLC
Line of Credit Facility [Line Items]
Capacity	1,151,200,000
Utilization	630,000,000
Unused Commitment	521,200,000
Unsecured and Committed | Voya Financial, Inc./ Roaring River IV LLC
Line of Credit Facility [Line Items]
Capacity	565,000,000
Utilization	287,000,000
Unused Commitment	$ 278,000,000