Consolidated Statements of Operations (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Revenues
Premiums and other considerations	$ 916.4	$ 803.6
Fees and other revenues	950.8	829.7
Net investment income (loss)	723.9	844.7
Net realized capital gains (losses), excluding impairment losses on available-for-sale securities	73.7	19.8
Net other-than-temporary impairment (losses) recoveries on available-for-sale securities	14.0	10.9
Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to (from) other comprehensive income	(21.5)	(30.1)
Net impairment (losses) recoveries on available-for-sale securities	(7.5)	(19.2)
Net realized capital gains (losses)	66.2	0.6
Total revenues	2,657.3	2,478.6
Expenses
Benefits, claims and settlement expenses	1,236.3	1,227.5
Dividends to policyholders	41.7	45.7
Operating expenses	921.2	829.0
Total expenses	2,199.2	2,102.2
Income (loss) before income taxes	458.1	376.4
Income taxes (benefits)	29.0	52.3
Net income (loss)	429.1	324.1
Net income (loss) attributable to noncontrolling interest	6.7	22.2
Net income (loss) attributable to Principal Financial Group, Inc.	422.4	301.9
Preferred stock dividends	8.2	8.2
Net income (loss) available to common stockholders	$ 414.2	$ 293.7
Earnings per common share
Basic earnings per common share (in dollars per share)	$ 1.41	$ 0.96
Diluted earnings per common share (in dollars per share)	$ 1.39	$ 0.95
Dividends declared per common share (in dollars per share)	$ 0.36	$ 0.28