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]
Comprehensive loss (income) attributable to noncontrolling interests	(100)
Total comprehensive income	78,129
Ending balance, common stock (in shares) at Jun. 30, 2021		45,850,599
Ending balance at Jun. 30, 2021	$ 1,557,060	$ 459	1,589,205	(39,316)	(3,633)	1,546,715	10,345
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]
Comprehensive loss (income) attributable to noncontrolling interests	361
Total comprehensive income	$ 29,712
Repurchases of common stock (in shares)	(1,196,175)
Ending balance, common stock (in shares) at Jun. 30, 2022	44,655,156	44,655,156
Ending balance at Jun. 30, 2022	$ 1,401,501	$ 447	$ 1,597,679	$ (205,906)	$ 0	$ 1,392,220	$ 9,281