Document And Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 13, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Document Period End Date	Dec. 31, 2014
Amendment Flag	false
Entity Registrant Name	STANCORP FINANCIAL GROUP INC
Entity Central Index Key	0001079577
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Common Stock, Shares Outstanding		42,142,630
Entity Public Float			$ 2,727,485,312
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	SFG
Closing Stock Price			$ 64