Revenues from Contracts with Customers - Disaggregation by Segment (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Revenues from Contracts with Customers - Disaggregation of Revenues
Total fees and other revenues per consolidated statements of operations	$ 1,145.3	$ 973.5
Operating Segments
Revenues from Contracts with Customers - Disaggregation of Revenues
Total segment revenue from contracts with customers	700.4	561.2
Operating Segments \| Retirement and Income Solutions
Revenues from Contracts with Customers - Disaggregation of Revenues
Total segment revenue from contracts with customers	158.5	61.3
Operating Segments \| Principal Global Investors
Revenues from Contracts with Customers - Disaggregation of Revenues
Total segment revenue from contracts with customers	382.9	332.3
Fees and other revenues not within the scope of revenue recognition guidance	5.5	4.3
Total fees and other revenues per consolidated statements of operations	388.4	336.6
Operating Segments \| Principal International
Revenues from Contracts with Customers - Disaggregation of Revenues
Total segment revenue from contracts with customers	109.5	114.9
Fees and other revenues not within the scope of revenue recognition guidance	1.3	1.7
Total fees and other revenues per consolidated statements of operations	110.8	116.6
Operating Segments \| U.S. Insurance Solutions
Revenues from Contracts with Customers - Disaggregation of Revenues
Total segment revenue from contracts with customers	16.6	15.7
Operating Segments \| Corporate
Revenues from Contracts with Customers - Disaggregation of Revenues
Total segment revenue from contracts with customers	32.9	37.0
Fees and other revenues not within the scope of revenue recognition guidance	(76.1)	(70.6)
Total fees and other revenues per consolidated statements of operations	(43.2)	(33.6)
Operating Segments \| Retirement and Income Solutions - Fee \| Retirement and Income Solutions
Revenues from Contracts with Customers - Disaggregation of Revenues
Total segment revenue from contracts with customers	156.4	58.4
Fees and other revenues not within the scope of revenue recognition guidance	280.5	271.8
Total fees and other revenues per consolidated statements of operations	436.9	330.2
Operating Segments \| Retirement and Income Solutions - Spread \| Retirement and Income Solutions
Revenues from Contracts with Customers - Disaggregation of Revenues
Total segment revenue from contracts with customers	2.1	2.9
Fees and other revenues not within the scope of revenue recognition guidance	3.1	4.9
Total fees and other revenues per consolidated statements of operations	5.2	7.8
Operating Segments \| Specialty Benefits insurance \| U.S. Insurance Solutions
Revenues from Contracts with Customers - Disaggregation of Revenues
Total segment revenue from contracts with customers	3.8	3.7
Fees and other revenues not within the scope of revenue recognition guidance	4.9	4.9
Total fees and other revenues per consolidated statements of operations	8.7	8.6
Operating Segments \| Individual Life insurance \| U.S. Insurance Solutions
Revenues from Contracts with Customers - Disaggregation of Revenues
Total segment revenue from contracts with customers	12.8	12.0
Fees and other revenues not within the scope of revenue recognition guidance	210.0	192.2
Total fees and other revenues per consolidated statements of operations	222.8	204.2
Reconciling Items
Revenues from Contracts with Customers - Disaggregation of Revenues
Fees and other revenues not within the scope of revenue recognition guidance	429.2	409.2
Pre-tax other adjustments	$ 15.7	$ 3.1

Amount of fees and commissions from financial services and banking activities and correspondent clearing, excluding contracts with customers and other pre-tax adjustments.

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Amount of fees and commissions related to financial service activities including, but not limited to, investment advisory and asset management services, recordkeeping and reporting services, administrative activities and sales of insurance and related services.

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The amount of other adjustments before tax in reconciling segment revenues from contracts with customers to consolidated revenues from fees and commissions.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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