Condensed Consolidated Statement Of Equity - USD ($) $ in Thousands	Total	Common Stock	Capital in Excess of Par Value	Cumulative Dividends in Excess of Net Income	Accumulated Other Comprehensive Loss	Total National Health Investors, Inc. Stockholders’ Equity	Noncontrolling Interests
Beginning balance, common stock (in shares) at Dec. 31, 2020		45,185,992
Beginning balance at Dec. 31, 2020	$ 1,522,945	$ 452	$ 1,540,946	$ (22,015)	$ (7,149)	$ 1,512,234	$ 10,711
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income	110,783
Ending balance, common stock (in shares) at Sep. 30, 2021		45,850,599
Ending balance at Sep. 30, 2021	$ 1,549,206	$ 459	1,590,194	(49,768)	(1,828)	1,539,057	10,149
Beginning balance, common stock (in shares) at Dec. 31, 2021	45,850,599	45,850,599
Beginning balance at Dec. 31, 2021	$ 1,516,983	$ 459	1,591,182	(84,558)	0	1,507,083	9,900
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income	$ 63,941
Repurchases of common stock (in shares)	(2,468,354)
Ending balance, common stock (in shares) at Sep. 30, 2022	43,388,742	43,388,742
Ending balance at Sep. 30, 2022	$ 1,315,448	$ 434	$ 1,598,385	$ (292,449)	$ 0	$ 1,306,370	$ 9,078