Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Consolidated Statements of Comprehensive Income
Net income (loss)	$ 190.0	$ 221.3
Other comprehensive income (loss), net:
Net unrealized gains (losses) on available-for-sale securities	(99.3)	161.3
Noncredit component of impairment losses on fixed maturities, available-for-sale	(11.3)	(0.9)
Net unrealized gains (losses) on derivative instruments	22.0	(3.5)
Foreign currency translation adjustment	54.4	59.6
Net unrecognized postretirement benefit obligation	13.8	8.7
Other comprehensive income (loss)	(20.4)	225.2
Comprehensive income (loss)	169.6	446.5
Comprehensive income (loss) attributable to noncontrolling interest	2.4	10.0
Comprehensive income (loss) attributable to Principal Financial Group, Inc.	$ 167.2	$ 436.5