Interim Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Noncontrolling Interest [Member]	Total
Balance at Jun. 30, 2016	$ 153	$ 218,896	$ 380,597	$ 71,897		$ 671,543
Balance (in shares) at Dec. 31, 2015	15,000,616
Balance at Dec. 31, 2015	$ 150	209,469	368,013	53,364		630,996
Net income attributable to National HealthCare Corporation			25,565			25,565
Net loss attributable to noncontrolling interest
Other comprehensive income				18,533		18,533
Stock–based compensation		494				494
Tax benefit (expense) from exercise of stock options		(1,134)				(1,134)
Shares sold – options exercised (in shares)	278,623
Shares sold – options exercised	$ 3	10,067				10,070
Dividends declared to common stockholders			(12,981)			(12,981)
Balance (in shares) at Jun. 30, 2016	15,279,239
Balance at Dec. 31, 2016	$ 152	211,457	391,934	66,068		669,611
Balance (in shares) at Dec. 31, 2015	15,000,616
Balance at Dec. 31, 2015	$ 150	209,469	368,013	53,364		$ 630,996
Shares sold – options exercised (in shares)						499,066
Balance (in shares) at Dec. 31, 2016	15,162,938
Balance at Jun. 30, 2017	$ 152	213,785	401,192	73,540	789	$ 689,458
Balance at Dec. 31, 2016	152	211,457	391,934	66,068		669,611
Net income attributable to National HealthCare Corporation			23,383			23,383
Net loss attributable to noncontrolling interest					(181)	(181)
Equity contributed by noncontrolling interest					970	970
Other comprehensive income				$ 7,472		7,472
Stock–based compensation		832				$ 832
Shares sold – options exercised (in shares)	32,092					31,992
Shares sold – options exercised		$ 1,496				$ 1,496
Dividends declared to common stockholders			$ (14,125)			$ (14,125)
Balance (in shares) at Jun. 30, 2017	15,195,030