Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consolidated Statements of Comprehensive Income
Net income (loss)	$ 1,428.5	$ 1,444.1	$ 1,553.7
Other comprehensive income (loss), net:
Net unrealized gains (losses) on available-for-sale securities	1,376.5	2,616.1	(1,529.6)
Noncredit component of impairment losses on fixed maturities, available-for-sale		3.0	26.4
Net unrealized gains (losses) on derivative instruments	(35.2)	(11.0)	16.0
Foreign currency translation adjustment	30.6	(78.7)	(287.6)
Net unrecognized postretirement benefit obligation	(24.9)	77.3	(60.9)
Other comprehensive income (loss)	1,347.0	2,606.7	(1,835.7)
Comprehensive income (loss)	2,775.5	4,050.8	(282.0)
Comprehensive income (loss) attributable to noncontrolling interest	34.5	53.6	2.7
Comprehensive income (loss) attributable to Principal Financial Group, Inc.	$ 2,741.0	$ 3,997.2	$ (284.7)