Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues
Premiums and other considerations	$ 1,276.0	$ 1,682.4	$ 2,558.4	$ 2,598.8
Fees and other revenues	916.8	901.5	1,772.7	1,852.3
Net investment income (loss)	799.2	789.9	1,560.9	1,513.8
Net realized capital gains (losses), excluding impairment losses on available-for-sale securities	43.7	(108.6)	228.4	(34.9)
Net other-than-temporary impairment (losses) recoveries on available-for-sale securities	(3.4)	(0.6)	(59.0)	13.4
Other-than-temporary impairment losses on fixed maturities, available-for-sale reclassified to (from) other comprehensive income	(6.6)	(5.4)	0.9	(26.9)
Net impairment (losses) recoveries on available-for-sale securities	(10.0)	(6.0)	(58.1)	(13.5)
Net realized capital gains (losses)	33.7	(114.6)	170.3	(48.4)
Total revenues	3,025.7	3,259.2	6,062.3	5,916.5
Expenses
Benefits, claims and settlement expenses	1,659.9	2,054.6	3,318.4	3,290.9
Dividends to policyholders	38.0	41.1	76.8	82.8
Operating expenses	927.9	869.0	1,827.4	1,790.2
Total expenses	2,625.8	2,964.7	5,222.6	5,163.9
Income (loss) before income taxes	399.9	294.5	839.7	752.6
Income taxes (benefits)	72.9	29.6	143.5	58.6
Net income (loss)	327.0	264.9	696.2	694.0
Net income (loss) attributable to noncontrolling interest	4.7	7.3	5.9	14.0
Net income (loss) attributable to Principal Financial Group, Inc.	322.3	257.6	690.3	680.0
Preferred stock dividends		8.3		16.5
Excess of redemption value over carrying value of preferred shares redeemed		8.2		8.2
Net income (loss) available to common stockholders	$ 322.3	$ 241.1	$ 690.3	$ 655.3
Earnings per common share
Basic earnings per common share (in dollars per share)	$ 1.11	$ 0.82	$ 2.37	$ 2.22
Diluted earnings per common share (in dollars per share)	1.10	0.81	2.35	2.20
Dividends declared per common share (in dollars per share)	$ 0.39	$ 0.38	$ 0.77	$ 0.74