Document and Entity Information Document - $ / shares	3 Months Ended
	Mar. 31, 2021	May 05, 2021	Dec. 31, 2020
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	1-11356
Entity Registrant Name	Radian Group Inc
Entity Tax Identification Number	23-2691170
Entity Address, Address Line One	1500 Market Street
Entity Address, City or Town	Philadelphia
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19102
City Area Code	215
Local Phone Number	231-1000
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	RDN
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		191,316,557
Entity Incorporation, State or Country Code	DE
Security Exchange Name	NYSE
Entity Central Index Key	0000890926
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false
Parent Company
Document Information [Line Items]
Common Stock, Par or Stated Value Per Share	$ 0.001		$ 0.001