Consolidated Statements of Financial Position - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Assets
Fixed maturities, available-for-sale (2016 and 2015 include $242.6 million and $257.4 million related to consolidated variable interest entities)	$ 55,281.3	$ 49,966.5
Fixed maturities, trading (2016 and 2015 include $82.4 million and $100.4 million related to consolidated variable interest entities)	656.9	686.8
Equity securities, available-for-sale	105.2	104.5
Equity securities, trading (2016 and 2015 include $689.0 million and $640.9 million related to consolidated variable interest entities)	1,331.1	1,202.7
Mortgage loans	12,685.8	12,339.4
Real estate (2016 and 2015 include $411.9 million and $354.5 million related to consolidated variable interest entities)	1,474.0	1,451.8
Policy loans	831.6	817.1
Other investments (2016 and 2015 include $360.5 million and $29.5 million related to consolidated variable interest entities and $82.1 million and $53.4 million measured at fair value under the fair value option)	4,321.5	3,251.7
Total investments	76,687.4	69,820.5
Cash and cash equivalents	2,255.4	2,564.8
Accrued investment income	563.0	545.6
Premiums due and other receivables	1,504.8	1,429.3
Deferred acquisition costs	3,173.7	3,276.1
Property and equipment	667.9	633.8
Goodwill	1,037.2	1,009.0
Other intangibles	1,358.5	1,359.2
Separate account assets (2016 and 2015 include $35,839.9 million and $33,300.4 million related to consolidated variable interest entities)	134,736.0	136,978.9
Other assets	1,090.3	1,043.1
Total assets	223,074.2	218,660.3
Liabilities
Contractholder funds (2016 and 2015 include $346.9 million and $338.9 million related to consolidated variable interest entities)	37,781.0	35,716.1
Future policy benefits and claims	27,996.1	25,856.5
Other policyholder funds	888.4	805.4
Short-term debt	25.9	181.1
Long-term debt (2016 and 2015 include $46.5 million and $42.8 million related to consolidated variable interest entities)	3,270.2	3,265.2
Income taxes currently payable	10.2	18.4
Deferred income taxes	1,234.7	697.2
Separate account liabilities (2016 and 2015 include $35,839.9 million and $33,300.4 million related to consolidated variable interest entities)	134,736.0	136,978.9
Other liabilities (2016 and 2015 include $317.0 million and $345.9 million related to consolidated variable interest entities, of which $58.6 million and $68.1 million are measured at fair value under the fair value option)	6,226.9	5,678.4
Total liabilities	212,169.4	209,197.2
Redeemable noncontrolling interest (2016 includes $266.6 million related to consolidated variable interest entities)	337.1	85.7
Stockholders' equity
Common stock, par value $.01 per share - 2,500.0 million shares authorized, 468.1 million and 466.2 million shares issued, and 288.0 million and 291.4 million shares outstanding in 2016 and 2015	4.7	4.7
Additional paid-in capital	9,615.7	9,544.8
Retained earnings (accumulated deficit)	7,339.6	6,875.9
Accumulated other comprehensive income (loss)	(19.3)	(882.5)
Treasury stock, at cost (180.1 million and 174.8 million shares in 2016 and 2015)	(6,441.0)	(6,231.3)
Total stockholders' equity attributable to Principal Financial Group, Inc.	10,499.7	9,311.6
Noncontrolling interest	68.0	65.8
Total stockholders' equity	10,567.7	9,377.4
Total liabilities and stockholders' equity	223,074.2	218,660.3
Series A
Stockholders' equity
Preferred stock, par value $.01 per share
Series B
Stockholders' equity
Preferred stock, par value $.01 per share