Schedule I - Financial Information of the Registrant (Parent Company) - Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of net income to cash provided by operating activities:
Net income attributable to Stewart	$ 11,373	$ 17,554	$ 22,377	$ (3,781)	$ 15,060	$ 10,944	$ 18,568	$ 4,087	$ 47,523	$ 48,659	$ 55,478
Add (deduct):
Depreciation and amortization									24,932	25,878	30,044
Decrease (increase) in receivables – net									5,280	(7,667)	7,759
Decrease (increase) in other assets – net									4,469	(4,512)	391
(Decrease) increase in payables and accrued liabilities – net									(12,002)	1,933	(3,888)
Income from subsidiaries									(1,940)	(2,163)	(2,834)
Other – net									404	483	0
Cash provided by operating activities									84,177	108,068	122,962
Investing activities:
Cash provided (used) by investing activities									9,379	(103,035)	(56,774)
Financing activities:
Proceeds from notes payable									14,530	56,493	57,758
Payments on notes payable									(20,118)	(56,467)	(60,339)
Cash paid on Class B Common Shares conversion									0	0	(12,000)
Repurchases of Common Stock									(1,175)	(727)	(1,053)
Purchase of remaining interest of consolidated subsidiary									(1,101)	(1,810)	(991)
Other – net									0	0	86
Cash used by financing activities									(47,758)	(43,595)	(59,342)
Increase (decrease) in cash and cash equivalents									41,988	(35,693)	6,705
Cash and cash equivalents at beginning of year				150,079				185,772	150,079	185,772	179,067
Cash and cash equivalents at end of year	192,067				150,079				192,067	150,079	185,772
Supplemental information:
Income taxes paid									12,854	(1,642)	15,265
Interest paid									4,214	3,466	3,020
Parent Company
Reconciliation of net income to cash provided by operating activities:
Net income attributable to Stewart									47,523	48,659	55,478
Add (deduct):
Depreciation and amortization									4	5	69
Decrease (increase) in receivables – net									922	(81)	245
Decrease (increase) in other assets – net									853	(1,576)	359
(Decrease) increase in payables and accrued liabilities – net									(4,476)	563	(496)
Income from subsidiaries									(40,669)	(36,062)	(47,421)
Other – net									(5,124)	1,705	(6,731)
Cash provided by operating activities									(967)	13,213	1,503
Investing activities:
Dividends from subsidiary									25,000	20,000	20,000
Purchase of property and equipment –net									0	0	(22)
Collections on notes receivables									24,900	23,375	27,500
Increases in notes receivables									(5,193)	(16,000)	0
Contributions to a subsidiary									0	(7,184)	0
Cash provided (used) by investing activities									44,707	20,191	47,478
Financing activities:
Proceeds from notes payable									0	16,000	20,000
Payments on notes payable									0	(10,000)	(25,125)
Dividends paid									(28,263)	(28,135)	(27,840)
Cash paid on Class B Common Shares conversion									0	0	(12,000)
Repurchases of Common Stock									(1,175)	(727)	(1,053)
Purchase of remaining interest of consolidated subsidiary									(1,101)	(1,810)	(991)
Other – net									0	0	86
Cash used by financing activities									(30,539)	(24,672)	(46,923)
Increase (decrease) in cash and cash equivalents									13,201	8,732	2,058
Cash and cash equivalents at beginning of year				$ 11,622				$ 2,890	11,622	2,890	832
Cash and cash equivalents at end of year	$ 24,823				$ 11,622				24,823	11,622	2,890
Supplemental information:
Income taxes paid									0	0	1
Interest paid									$ 3,849	$ 3,128	$ 2,716