Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
Oct. 31, 2017	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
Quarterly Financial Information Disclosure [Abstract]
Net sales		$ 241,845	$ 284,178	$ 308,007	$ 244,779	$ 231,681	$ 262,476	$ 263,002	$ 219,867	$ 1,078,809	$ 977,025	$ 860,661
Cost of sales		143,409	150,282	167,442	137,157	129,777	143,338	140,139	120,390	598,290	533,644	450,781
Gross profit		98,436	133,896	140,565	107,622	101,904	119,138	122,863	99,477	480,519	443,381	409,880
Research and development and other engineering		10,216	10,441	11,249	11,150	12,565	11,265	11,967	11,819	43,056	47,616	46,248
Selling		26,278	26,879	29,201	27,573	28,753	27,867	28,646	29,637	109,931	114,903	98,343
General and administrative		45,195	37,356	39,354	37,188	36,236	33,441	37,586	35,845	159,093	143,107	124,859
Total operating expenses		81,689	74,676	79,804	75,911	77,554	72,573	78,199	77,301	312,080	305,626	269,450
Net gain on disposal of assets		8,810	460	125	1,184	13	147	(50)	50	10,579	160	780
Impairment of goodwill		6,686	0	0	0	0	0	0	0	6,686	0	0
Income from operations		18,871	59,680	60,886	32,895	24,363	46,712	44,614	22,226	172,332	137,915	141,210
Loss in equity investment, before tax		11	30	(2)	24	33	13	12	28	63	86	0
Foreign exchange gain (loss), net		(571)	1,242	(142)	(99)	342	(16)	523	403	430	1,252	(1,733)
Interest (expense) income, net		(239)	(58)	(184)	(90)	(104)	(296)	(199)	(189)
Gain (adjustment) on bargain purchase of a business		0	0	0	0	0	2,052	0	(8,388)
Loss on disposal of a business	$ (200)	0	0	0	0	(654)	443	0	0	0	(211)	0
Income before taxes		18,050	60,834	60,562	32,682	23,914	44,778	44,926	30,800	172,128	144,418	138,900
Provision for income taxes		5,293	16,473	16,476	7,253	10,829	16,581	16,712	7,679	45,495	51,801	49,166
Net income		$ 12,757	$ 44,361	$ 44,086	$ 25,429	$ 13,085	$ 28,197	$ 28,214	$ 23,121	$ 126,633	$ 92,617	$ 89,734
Earnings per share of common stock:
Basic		$ 0.28	$ 0.96	$ 0.95	$ 0.55	$ 0.28	$ 0.60	$ 0.59	$ 0.49	$ 2.74	$ 1.95	$ 1.87
Diluted		0.28	0.95	0.94	0.54	0.27	0.59	0.59	0.48	2.72	1.94	1.86
Cash dividends declared per share of common stock		$ 0.22	$ 0.22	$ 0.22	$ 0.21	$ 0	$ 0.42	$ 0.21	$ 0.18	$ 0.87	$ 0.81	$ 0.70

Business Combination, Bargain Purchase, Gain (Loss) Recognized, Amount

No definition available.

Name:	ssd_BusinessCombinationBargainPurchaseGainLossRecognizedAmount
Namespace Prefix:	ssd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use; (3) to conduct internal product testing; (4) or to provide engineering support to customers in the form of testing services or product uses, specifications or requirements.

+ References

No definition available.