Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenues
Premiums and other considerations	$ 1,557.1	$ 875.8	$ 4,155.9	$ 2,514.8
Fees and other revenues	891.9	884.5	2,744.2	2,569.7
Net investment income (loss)	753.5	770.4	2,267.3	2,444.1
Net realized capital gains (losses), excluding impairment losses on available-for-sale securities	46.0	(24.5)	11.1	105.0
Net other-than-temporary impairment (losses) recoveries on available-for-sale securities	(6.5)	(7.3)	6.9	18.5
Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to (from) other comprehensive income	(1.1)	(14.6)	(28.0)	(82.5)
Net impairment (losses) recoveries on available-for-sale securities	(7.6)	(21.9)	(21.1)	(64.0)
Net realized capital gains (losses)	38.4	(46.4)	(10.0)	41.0
Total revenues	3,240.9	2,484.3	9,157.4	7,569.6
Expenses
Benefits, claims and settlement expenses	1,869.6	1,113.8	5,160.5	3,609.7
Dividends to policyholders	40.7	44.2	123.5	134.5
Operating expenses	961.4	932.5	2,751.6	2,647.7
Total expenses	2,871.7	2,090.5	8,035.6	6,391.9
Income (loss) before income taxes	369.2	393.8	1,121.8	1,177.7
Income taxes (benefits)	68.3	141.0	126.9	281.6
Net income (loss)	300.9	252.8	994.9	896.1
Net income (loss) attributable to noncontrolling interest	0.5	3.9	14.5	30.7
Net income (loss) attributable to Principal Financial Group, Inc.	300.4	248.9	980.4	865.4
Preferred stock dividends		8.2	16.5	24.7
Excess of redemption value over carrying value of preferred shares redeemed			8.2
Net income (loss) available to common stockholders	$ 300.4	$ 240.7	$ 955.7	$ 840.7
Earnings per common share
Basic earnings per common share (in dollars per share)	$ 1.02	$ 0.78	$ 3.24	$ 2.78
Diluted earnings per common share (in dollars per share)	1.01	0.77	3.20	2.75
Dividends declared per common share (in dollars per share)	$ 0.38	$ 0.34	$ 1.12	$ 0.94