Capital Stock - Share-based and Other Compensation Programs (Details)	6 Months Ended
	Jun. 30, 2025 $ / shares shares
Performance Based RSUs Equity Settled
Number of Shares
Outstanding, Beginning Balance (in shares) | shares	2,639,190	[1]
Granted (in shares) | shares	492,170	[2]
Performance adjustment (in shares) | shares	549,540	[3]
Vested (in shares) | shares	(1,158,485)	[4]
Forfeited (in shares) | shares	(11,216)
Outstanding, Ending Balance (in shares) | shares	2,511,199	[1]
Weighted Average Grant Date Fair Value
Outstanding, Beginning Balance (in usd per share) | $ / shares	$ 22.57	[1]
Granted (in usd per share) | $ / shares	30.96	[2]
Performance adjustment (in usd per share) | $ / shares	0	[3]
Vested (in usd per share) | $ / shares	20.19	[4]
Forfeited (in usd per share) | $ / shares	29.34
Outstanding, Ending Balance (in usd per share) | $ / shares	$ 24.61	[1]
Timed-Vested RSUs Equity Settled
Number of Shares
Outstanding, Beginning Balance (in shares) | shares	1,589,396	[1]
Granted (in shares) | shares	387,072	[2]
Performance adjustment (in shares) | shares	0	[3]
Vested (in shares) | shares	(604,393)	[4]
Forfeited (in shares) | shares	(7,747)
Outstanding, Ending Balance (in shares) | shares	1,364,328	[1]
Weighted Average Grant Date Fair Value
Outstanding, Beginning Balance (in usd per share) | $ / shares	$ 20.75	[1]
Granted (in usd per share) | $ / shares	33.17	[2]
Performance adjustment (in usd per share) | $ / shares	0	[3]
Vested (in usd per share) | $ / shares	21.95	[4]
Forfeited (in usd per share) | $ / shares	26.88
Outstanding, Ending Balance (in usd per share) | $ / shares	$ 23.71	[1]

[1] Outstanding RSUs represent shares that have not yet been issued because not all conditions necessary to earn the right to benefit from the instruments have been satisfied. For performance-based awards, the final number of RSUs distributed depends on: (i) the cumulative growth in Radian’s book value per share adjusted for certain defined items over the respective three-year performance period and, for the performance-based RSUs granted starting in 2023, a modifier based on a comparison of our total shareholder return to the total shareholder return of certain of our peers and (ii) with the exception of certain retirement-eligible employees, continued service through the vesting date, which could result in changes to the number of vested RSUs.

[2] For performance-based RSUs, amount represents the number of target shares at grant date.

[3] For performance-based RSUs, amount represents the difference between the number of shares vested at settlement, which can range from 0 to 200% of target depending on results over the applicable performance periods, and the number of target shares at the grant date.

[4] For both performance-based and time-based RSUs, amount represents the number of shares vested during the period, including the impact of performance adjustments for performance-based awards.