Discontinued Operations and Assets and Liabilities Held-for-Sale - Condensed Consolidated Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues and other income:
Sale of real estate and water assets	$ 136	$ 476	$ 25,276	$ 607
Other income, net	69	689	9,756	2,193
Total revenues and other income	205	1,165	35,032	2,800
Cost of sales and expenses:
Cost of real estate and water assets sold	55	252	12,604	316
General, administrative, and other	2,943	5,649	9,865	16,054
Impairment loss on intangible and long-lived assets		201		201
Depreciation and amortization	24	162	159	702
Total cost of sales and expenses	3,022	6,264	22,628	17,273
Income (loss) from continuing operations before income taxes	(2,817)	(5,099)	12,404	(14,473)
Benefit for federal and state income taxes	(292)	530	(3,419)	712
Income (loss) from discontinued operations, net of tax	(5,269)	2,710	3,053	4,195
Gain (loss) on sale and impairment loss on classification of assets as held-for-sale, net of tax	2,094	2	(9,309)	(1,858)
Net income (loss) from discontinued operations, net of tax	(3,175)	2,712	(6,256)	2,337
Net income (loss)	(6,284)	(1,857)	2,729	(11,424)
Net (income) loss attributable to noncontrolling interests	1,645	(1,043)	(1,150)	(1,676)
Net income (loss) attributable to PICO Holdings, Inc.	(4,639)	(2,900)	1,579	(13,100)
Discontinued Operations, Held-for-sale
Revenues and other income:
Sale of real estate and water assets					$ 633	$ 3,856	$ 1,220
Impairment loss on investment in unconsolidated affiliate					(2,170)	(20,696)	(1,078)
Other income, net					9,471	4,472	1,077
Total revenues and other income					7,934	(12,368)	1,219
Cost of sales and expenses:
Cost of real estate and water assets sold					326	1,239	738
General, administrative, and other					32,830	20,027	24,156
Impairment loss on intangible and long-lived assets					201	2,085	10,219
Depreciation and amortization					865	1,660	2,385
Total cost of sales and expenses					34,222	25,011	37,498
Income (loss) from continuing operations before income taxes					(26,288)	(37,379)	(36,279)
Benefit for federal and state income taxes					1,135	2,961	2,450
Equity in loss of unconsolidated affiliate						(3,422)	(2,076)
Loss from continuing operations					(25,153)	(37,840)	(35,905)
Income (loss) from discontinued operations, net of tax	(5,269)	2,710	3,053	4,195	13,899	(24,310)	(23,700)
Gain (loss) on sale and impairment loss on classification of assets as held-for-sale, net of tax	2,094		(9,311)		(1,775)	(18,729)
Net income (loss) from discontinued operations, net of tax	$ (3,175)	$ 2,712	$ (6,256)	$ 2,337	12,124	(43,039)	(23,700)
Net income (loss)					(13,029)	(80,879)	(59,605)
Net (income) loss attributable to noncontrolling interests					(8,836)	(979)	7,180
Net income (loss) attributable to PICO Holdings, Inc.					$ (21,865)	$ (81,858)	$ (52,425)