Consolidated Statements of Financial Position - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Assets
Fixed maturities, available-for-sale (2017 and 2016 include $268.0 million and $232.5 million related to consolidated variable interest entities)	$ 59,388.4	$ 54,846.1
Fixed maturities, trading (2017 and 2016 include $0.0 million and $82.4 million related to consolidated variable interest entities)	566.0	398.4
Equity securities, available-for-sale	96.0	98.9
Equity securities, trading (2017 and 2016 include $811.4 million and $721.9 million related to consolidated variable interest entities)	1,770.6	1,413.4
Mortgage loans	14,150.5	13,230.2
Real estate (2017 and 2016 include $370.3 million and $305.7 million related to consolidated variable interest entities)	1,736.7	1,368.8
Policy loans	808.3	823.8
Other investments (2017 and 2016 include $139.8 million and $89.8 million related to consolidated variable interest entities and $61.0 million and $86.2 million measured at fair value under the fair value option)	3,586.2	3,655.9
Total investments	82,102.7	75,835.5
Cash and cash equivalents	2,470.8	2,719.6
Accrued investment income	610.6	580.6
Premiums due and other receivables	1,469.8	1,361.9
Deferred acquisition costs	3,540.7	3,380.2
Property and equipment	759.5	699.0
Goodwill	1,068.8	1,020.8
Other intangibles	1,314.7	1,325.3
Separate account assets (2017 and 2016 include $41,540.8 million and $35,844.1 million related to consolidated variable interest entities)	159,272.7	139,832.6
Other assets	1,330.9	1,258.8
Total assets	253,941.2	228,014.3
Liabilities
Contractholder funds (2017 and 2016 include $380.6 million and $358.7 million related to consolidated variable interest entities)	38,082.5	37,953.6
Future policy benefits and claims	33,019.3	29,000.7
Other policyholder funds	922.3	890.4
Short-term debt	39.5	51.4
Long-term debt	3,178.4	3,125.7
Income taxes currently payable	16.7	12.9
Deferred income taxes	1,092.5	972.4
Separate account liabilities (2017 and 2016 include $41,540.8 million and $35,844.1 million related to consolidated variable interest entities)	159,272.7	139,832.6
Other liabilities (2017 and 2016 include $270.2 million and $284.1 million related to consolidated variable interest entities, of which $0.0 million and $59.9 million are measured at fair value under the fair value option)	5,294.1	5,783.3
Total liabilities	240,918.0	217,623.0
Redeemable noncontrolling interest (2017 and 2016 include $52.4 million and $58.8 million related to consolidated variable interest entities)	101.3	97.5
Stockholders' equity
Common stock, par value $.01 per share - 2,500.0 million shares authorized, 474.1 million and 469.2 million shares issued, and 289.0 million and 287.7 million shares outstanding in 2017 and 2016	4.7	4.7
Additional paid-in capital	9,925.2	9,686.0
Retained earnings (accumulated deficit)	9,482.9	7,720.4
Accumulated other comprehensive income (loss)	165.5	(675.2)
Treasury stock, at cost (185.1 million and 181.5 million shares in 2017 and 2016)	(6,729.0)	(6,508.6)
Total stockholders' equity attributable to Principal Financial Group, Inc.	12,849.3	10,227.3
Noncontrolling interest	72.6	66.5
Total stockholders' equity	12,921.9	10,293.8
Total liabilities and stockholders' equity	$ 253,941.2	$ 228,014.3