Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Consolidated Statements of Comprehensive Income
Net income (loss)	$ 1,253.2	$ 1,176.4	$ 936.1
Other comprehensive income (loss), net:
Net unrealized gains (losses) on available-for-sale securities	(470.7)	324.7	(540.2)
Noncredit component of impairment losses on fixed maturities, available-for-sale	19.1	61.9	6.9
Net unrealized gains (losses) on derivative instruments	19.2	61.1	(1.8)
Foreign currency translation adjustment	(471.6)	(336.6)	(269.4)
Net unrecognized postretirement benefit obligation	(39.1)	(255.2)	332.6
Other comprehensive income (loss)	(943.1)	(144.1)	(471.9)
Comprehensive income (loss)	310.1	1,032.3	464.2
Comprehensive income (loss) attributable to noncontrolling interest	(1.3)	21.0	8.6
Comprehensive income (loss) attributable to Principal Financial Group, Inc.	$ 311.4	$ 1,011.3	$ 455.6