Condensed Consolidated Statement Of Equity - USD ($) $ in Thousands	Total	Total National Health Investors, Inc. Stockholders’ Equity	Common Stock	Capital in Excess of Par Value	Retained Earnings	Cumulative Dividends	Noncontrolling Interests
Beginning balance, common stock (in shares) at Dec. 31, 2021			45,850,599
Beginning balance at Dec. 31, 2021	$ 1,516,983	$ 1,507,083	$ 459	$ 1,591,182	$ 2,416,713	$ (2,501,271)	$ 9,900
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued on stock options exercised (in shares)	56,832
Ending balance, common stock (in shares) at Sep. 30, 2022			43,388,742
Ending balance at Sep. 30, 2022	$ 1,315,448	1,306,370	$ 434	1,598,385	2,329,327	(2,621,776)	9,078
Beginning balance, common stock (in shares) at Dec. 31, 2021			45,850,599
Beginning balance at Dec. 31, 2021	$ 1,516,983	1,507,083	$ 459	1,591,182	2,416,713	(2,501,271)	9,900
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchases of common stock (in shares)	(2,468,354)
Repurchases of common stock	$ (151,600)
Ending balance, common stock (in shares) at Dec. 31, 2022	43,388,742		43,388,742
Ending balance at Dec. 31, 2022	$ 1,280,081	1,270,225	$ 434	1,599,427	2,331,190	(2,660,826)	9,856
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued on stock options exercised (in shares)	5,166
Ending balance, common stock (in shares) at Sep. 30, 2023	43,409,841		43,409,841
Ending balance at Sep. 30, 2023	$ 1,270,903	$ 1,260,111	$ 434	$ 1,602,892	$ 2,434,799	$ (2,778,014)	$ 10,792