Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Jun. 30, 2014	Mar. 09, 2015
Document Information [Line Items]
Entity Registrant Name	NATIONAL WESTERN LIFE INSURANCE CO
Entity Central Index Key	0000070684
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2014
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float		$ 568,168,220
Common Class A [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding			3,436,166
Common Class B [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding			200,000