Condensed Consolidated Statement Of Equity - USD ($) $ in Thousands	Total	Common Stock	Capital in Excess of Par Value	Retained Earnings	Cumulative Dividends	Total National Health Investors, Inc. Stockholders’ Equity	Noncontrolling Interests
Beginning balance, common stock (in shares) at Dec. 31, 2021		45,850,599
Beginning balance at Dec. 31, 2021	$ 1,516,983	$ 459	$ 1,591,182	$ 2,416,713	$ (2,501,271)	$ 1,507,083	$ 9,900
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued on stock options exercised (in shares)	10,000
Ending balance, common stock (in shares) at Jun. 30, 2022		44,655,156
Ending balance at Jun. 30, 2022	$ 1,401,501	$ 447	1,597,679	2,376,820	(2,582,726)	1,392,220	9,281
Beginning balance, common stock (in shares) at Dec. 31, 2021		45,850,599
Beginning balance at Dec. 31, 2021	$ 1,516,983	$ 459	1,591,182	2,416,713	(2,501,271)	1,507,083	9,900
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchases of common stock (in shares)	(2,468,354)
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	$ 434	1,599,427	2,331,190	(2,660,826)	1,270,225	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 Jun. 30, 2023	43,409,841	43,409,841
Ending balance at Jun. 30, 2023	$ 1,280,203	$ 434	$ 1,602,026	$ 2,405,453	$ (2,738,945)	$ 1,268,968	$ 11,235