Document and Entity Information	3 Months Ended
	Mar. 31, 2013	May 05, 2013 Common Class A [Member]	May 05, 2013 Common Class B [Member]
Entity 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-Q
Document Period End Date	Mar. 31, 2013
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		3,434,763	200,000