Consolidated Statement of Stockholders' Equity - USD ($) $ in Thousands	Total	COMMON STOCK, AMOUNT	PAID-IN CAPITAL	ACCUMULATED OTHER COMPREHENSIVE INCOME(LOSS)	TREASURY STOCK, AT COST	RETAINED EARNINGS	TOTAL IHC STOCKHOLDERS' EQUITY	NON-CONTROLLING INTERESTS
Treasury Stock, Shares					(3,735,173)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Dec. 31, 2017	$ 434,243	$ 18,625	$ 124,538	$ (4,598)	$ (63,404)	$ 356,383	$ 431,544	$ 2,699
Common Stock, Shares, Issued at Dec. 31, 2017		18,625,458
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	28,834					28,482	28,482	352
Other Comprehensive Income (Loss), Net of Tax	(3,362)			(3,362)			(3,362)	0
Treasury Stock, Value, Acquired, Cost Method	$ (4,019)				$ (4,019)		(4,019)	0
Treasury Stock, Shares, Acquired	(135,311)				(135,311)
Dividends, Common Stock, Cash	$ (4,468)					(4,468)	(4,468)	0
Sharebased Compensation Effect On Stockholders Equity	888		(143)		$ 1,031		888	0
Sharebased Compensation Effect On Stockholders Equity, Shares Issued					123,274
Distributions to noncontrolling interests	(272)						0	(272)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Dec. 31, 2018	$ 451,431	$ 18,625	124,395	(8,310)	$ (66,392)	380,431	448,749	2,682
Common Stock, Shares, Issued at Dec. 31, 2018	18,625,458	18,625,458
Treasury Stock, Shares	(3,747,210)				(3,747,210)
Cumulative Effect of New Accounting Principle in Period of Adoption	$ (413)			(350)		34	(316)	(97)
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	12,515					12,396	12,396	119
Other Comprehensive Income (Loss), Net of Tax	9,522			9,522			9,522	0
Treasury Stock, Value, Acquired, Cost Method	$ (4,051)				$ (4,051)		(4,051)	0
Treasury Stock, Shares, Acquired	(108,646)				(108,646)
Dividends, Common Stock, Cash	$ (5,963)					(5,963)	(5,963)	0
Sharebased Compensation Effect On Stockholders Equity	105		(614)		$ 719		105	0
Sharebased Compensation Effect On Stockholders Equity, Shares Issued					95,339
Distributions to noncontrolling interests	(403)						0	(403)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Dec. 31, 2019	$ 459,712	$ 18,625	122,717	$ 1,212	$ (69,724)	$ 386,864	459,694	18
Common Stock, Shares, Issued at Dec. 31, 2019	18,625,458	18,625,458
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	$ (3,413)		(1,033)				(1,033)	(2,380)
Other	$ (31)		$ (31)				$ (31)	$ 0
Treasury Stock, Shares	(3,760,517)				(3,760,517)