Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Consolidated Statements of Comprehensive Income
Net income (loss)	$ 369.2	$ 429.1
Other comprehensive income (loss), net:
Net unrealized gains (losses) on available-for-sale securities	404.4	57.1
Noncredit component of impairment losses on fixed maturities, available-for-sale	(4.2)	13.5
Net unrealized gains (losses) on derivative instruments	1.3	27.8
Foreign currency translation adjustment	129.7	(132.6)
Net unrecognized postretirement benefit obligation	8.0	12.0
Other comprehensive income (loss)	539.2	(22.2)
Comprehensive income (loss)	908.4	406.9
Comprehensive income (loss) attributable to noncontrolling interest	4.7	0.4
Comprehensive income (loss) attributable to Principal Financial Group, Inc.	$ 903.7	$ 406.5