Description of the Business and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The accompanying condensed consolidated financial statements have been prepared in accordance with U.S. GAAP.
Principles of Consolidation	The accompanying condensed consolidated financial statements include the accounts of SGC and its wholly owned subsidiaries, and those subsidiaries in which we have a controlling financial interest. Investments in other entities in which we do not have a controlling financial interest but we exert significant influence are accounted for in our condensed consolidated financial statements using the equity method of accounting. All intercompany balances and transactions have been eliminated in consolidation. In the opinion of the Company and its management, we have made all adjustments necessary to present fairly our consolidated financial position, results of operations and comprehensive loss and cash flows for the periods presented. Such adjustments are of a normal, recurring nature. These unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes included in our 2017 10-K. Interim results of operations are not necessarily indicative of results of operations to be expected for a full year.
New Accounting Guidance	New Accounting Guidance - Recently Adopted In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers. ASU 2014-09 combined with all subsequent amendments (collectively ASC 606) provides guidance outlining a single comprehensive revenue model in accounting for revenue from contracts with customers. ASC 606 supersedes existing revenue recognition guidance, including industry-specific guidance, and replaces it with a five-step revenue model with a core principle that "an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services." This guidance is effective for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years. We adopted this guidance effective January 1, 2018 using a modified retrospective application approach. See our 2017 10-K Note 1 for the anticipated annual impact on our consolidated financial statements and Note 2 in this Quarterly Report on Form 10-Q for our revenue recognition policy and the quarterly impact of our adoption of ASC 606. The FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business in 2017. The new guidance clarifies the definition of a business in order to allow for the evaluation of whether transactions should be accounted for as acquisitions or disposals of assets or businesses. We adopted this guidance effective January 1, 2018, and this adoption did not have a material effect on our consolidated financial statements. The FASB issued ASU No. 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost in 2017. We adopted this guidance effective January 1, 2018. This guidance requires an employer to report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of operating income, if one is presented, which for us means that certain immaterial amounts will be classified within interest expense as compared to the previous classification within SG&A. We are also required to describe which line items are used to present the other components of net benefit cost if such financial statement line items are separately presented; otherwise, we must disclose the line items in which such costs are presented. The FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities in 2017. We early adopted this guidance during the first quarter of 2018, which simplifies the application of hedge accounting guidance, and creates greater transparency for results presented on the face of the financial statements and footnotes. Our adoption did not have a material effect on our consolidated financial statements. New Accounting Guidance - Not Yet Adopted The FASB issued ASU No. 2016-02, Leases (Topic 842) in 2016. The amended guidance is intended to increase transparency and comparability among organizations by recognizing lease assets and liabilities on the balance sheet and disclosing key information about leasing arrangements. The adoption of this guidance is expected to result in a significant portion of our operating leases, where we are the lessee, to be recognized on our consolidated balance sheet. The guidance requires lessees and lessors to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. This guidance is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years, with earlier adoption permitted. We are currently evaluating the impact of adopting this guidance. The FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326) in 2016. The new guidance replaces the incurred loss impairment methodology in current U.S. GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. For trade and other receivables, loans and other financial instruments, we will be required to use a forward-looking expected loss model rather than the incurred loss model for recognizing credit losses which reflects losses that are probable. The new guidance will be effective for us beginning January 1, 2020, with early adoption permitted beginning January 1, 2018. Application of the amendments is through a cumulative-effect adjustment to retained earnings as of the effective date. We are currently evaluating the impact of adopting this guidance.
Revenue Recognition	General We evaluate the recognition of revenue and rental income based on the criteria set forth in ASC 606 or ASC 840, as appropriate. Revenue is recognized when control of the promised goods or services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. This condition normally is met when the product has been delivered or upon performance of services. Revenue is reported net of incentive rebates and discounts. We made an accounting policy election to exclude from the measurement of the transaction price sales taxes and all other items of a similar nature, and also elected to account for shipping and handling activities as a fulfillment of our promise to transfer the goods. Accordingly, shipping and handling costs are included in cost of sales. Our credit terms are predominately short term in nature. We also grant extended payment terms under certain contracts, primarily where the sale is secured by the related equipment sold, and generally only in certain Gaming segment contracts with customers. For these contracts with customers for which the financing component is determined to be significant to the contract, the contract transaction price is adjusted for the effect of a financing component (time value of money). We have not applied the significant financing component guidance to transactions with financing terms of 12 months or less. Any sales commissions associated with the sale or placement of our products and services are expensed as incurred as contracts associated with sales commissions are generally completed within a one-year period. The primary types of revenue impacted by the adoption of ASC 606 were Gaming operations and Lottery instant products. Each of these is described separately below. We had other balance sheet adoption impacts that, combined with the preceding, resulted in a net increase to opening accumulated loss of $10.9 million as of January 1, 2018. As part of the adoption of ASC 606, we increased contract liabilities by $9.7 million primarily associated with Lottery instant products licensing and player loyalty contracts for which we determined that the promises in the related contracts were part of a single performance obligation under ASC 606. In addition, we reduced previously recorded deferred costs net of newly established contract assets by $11.4 million related to licensing in certain customized lottery software contracts for which we concluded that we were unable to recognize revenue for delivered elements under ASC 985-605 due to the lack of vendor-specific objective evidence for undelivered elements and for which we were required to estimate the standalone selling price of delivered performance obligations under ASC 606. Combined, we expect all other adoption impacts other than Gaming operations and Lottery instant products to have less than a $10.0 million impact on revenue and operating income in the aggregate for the remainder of 2018. Contracts with Customers with Multiple Promised Goods and Services We enter into contracts with customers that include multiple promises (such as gaming machines, gaming systems hardware and software, installation, service and maintenance, product support or lottery systems and hardware, installation and maintenance bundled promises). For such contracts, the transaction price is allocated to each distinct performance obligation using an estimate of stand-alone selling price. The stand-alone selling price is generally based on observable prices or a cost plus margin approach. We also use the residual method when observable prices are uncertain or highly variable, primarily with respect to certain of our software licenses. The establishment of stand-alone selling price requires judgment as to whether there is a sufficient quantity of items sold or substantively renewed on a stand-alone basis and those prices demonstrate an appropriate level of concentration to conclude that a stand-alone selling price exists. The guidance in ASC 606 requires that we apply judgments or estimates to determine both the performance obligations and the stand-alone selling prices of identified performance obligations. Contracts with multiple promised goods and services described above will often involve significant judgment in determining whether each promise is distinct or should be combined with other promises in such contracts in concluding on the distinct performance obligations for such contracts. Such judgment generally requires an assessment of the level of integration and interdependency between individual components particularly in our gaming systems and certain digital contracts with customers. Associated with these same contracts, we also apply significant judgment to determine the stand-alone selling prices of the identified performance obligations. In certain contracts with customers, we bundle the selling price for multiple promised goods or services or we may license systems for which the solutions we provide are highly customized and therefore the prices we charge are either uncertain, highly variable, or both. Gaming Operations Gaming operations revenues are generated by providing customers access to proprietary land-based gaming equipment, table game products and VLTs under a variety of recurring operating, service, or rental contracts, for which consideration is based upon a percentage of Coin-in, a percentage of Net win, or a fixed daily/monthly fee, with variability generally resolved in the reporting period. For these contracts with customers, we generally transfer control and recognize revenue or rental income over time based on the amount we expect to receive as described and classify such revenue or rental income as services revenue. Payments from customers under these contracts are typically due on a monthly basis. Jackpot expense for our WAP services is recorded as a reduction to revenue, which decreased revenue and cost of services by $6.5 million and $10.9 million for the three and six months ended June 30, 2018, respectively. This change in classification has no impact on operating income or net loss. There was $5.3 million and $12.4 million of such amounts presented as cost of services for the three and six months ended June 30, 2017, respectively. Gaming Machine Sales These contracts with customers include the sale of gaming machines, including game content, electronic table game products and parts (including game themes and conversion kits). We transfer control and recognize revenue from the sale of gaming machines at a point in time upon delivery of gaming machines to our customers or distributors pursuant to the terms of the contract. If the sale of gaming machines includes multiple promised goods and services, these contracts are accounted for as described in the "Contracts with Customers with Multiple Promised Goods and Services" section above. Our credit terms are predominately short term in nature. Gaming Systems Gaming systems contracts with customers can include a comprehensive suite of technology solutions provided to gaming operators, including perpetual licenses to core system solutions and non-core system solutions and other applications and tools. Gaming systems products also include the iVIEW^® touch screen display, which facilitates the player experience, bonus features, customer service, and employee functions and ongoing hardware and software maintenance services and upgrades. Determination of performance obligations and timing of the transfer of control varies by contract. Generally, these contracts contain multiple promised goods and services, including the following: (i) core system software license; (ii) non-core system software license(s); (iii) professional services; (iv) system-based hardware; (v) in-game hardware products; and (vi) software and hardware maintenance and product support. Control transfers and we recognize revenue from the sale of perpetual gaming systems licenses and various hardware products at a point in time when the gaming system is available for use by a customer which is no earlier than the commencement of the license term, and for the hardware products upon delivery. For contracts that include new core gaming system installations, control is not considered transferred until control of the core gaming system license is transferred as the additional promises are generally highly dependent on the core gaming system. Software and hardware maintenance and product support services are considered stand-ready obligations, therefore control transfers and revenue is recognized over time over the term of the maintenance and support period. If a gaming systems contract includes multiple promised goods and services, these contracts are accounted for as described in the "Contracts with Customers with Multiple Promised Goods and Services" section above. Table Products Table products revenue is generated from supplying and maintaining or selling table game products, primarily including automatic card shufflers, deck checkers, table roulette chip sorters and other land-based table gaming equipment. We transfer control and recognize revenue from the sale of table products at a point in time upon delivery to our customers or distributors pursuant to the terms of the contract. Supply and maintenance contracts, for which consideration is primarily based on a fixed monthly fee, are considered stand-ready obligations, therefore control transfers and revenue is recognized over time over the term of the supply and maintenance period. Such contracts are generally short-term in nature. We also license our proprietary table games content, for which revenue is recognized at a point in time under the licensing of intellectual property guidance as such licenses are functional licenses. Lottery Instant Products Our instant products revenue is primarily generated under long-term contracts to supply instant products and provide related services to our Lottery customers. For instant products that are sold on a PPU and POS basis, we generally have a single performance obligation of a promise to supply the instant products. Control transfers and we recognize revenue from the sale of such instant products when the lotteries have taken delivery of shipments of instant products pursuant to the terms of the contract. For instant products that are sold on a POS basis, we are compensated based on retail sales, therefore the timing difference between the recognition of revenue, the billing of our customers and the receipt of payments depends on retail sales. Contract assets resulting from these contracts remain until we have the contractual ability to invoice and collect from customers (which occurs upon retail sales). For our CSP contracts in which we perform all of the services necessary to operate the associated lottery’s integrated instant product operations and for which we are compensated based on retail sales, our single performance obligation is a promise to perform a series of stand-ready services to operate and manage instant gaming programs for the lotteries in their entirety. Revenue is recognized over time as measured by an appropriate measure of progress toward satisfying our performance obligation, which we have determined to be when a lottery retailer activates any associated instant tickets, as this is the point at which we have transferred control over the associated instant tickets and perform no more services related to such instant tickets. The guidance in ASC 606 requires that we apply judgment to determine the timing of control transfer of performance obligations in our Lottery instant products contracts. For instant products that are sold under POS contracts, we generally have a single performance obligation of a promise to supply the instant products. The determination of when control transfers requires significant judgment because lotteries take delivery of shipments of instant products, but we retain the risk of such inventory until retail sales of such tickets takes place. We have determined control transfers upon delivery to a lottery-controlled warehouse, because we do not have the ability to direct the use of such instant products subsequent to delivery. As disclosed in the first quarter of 2018, there was an $8.1 million and $6.3 million increase in revenue and Lottery Business Segment AEBITDA, respectively, associated with instant products sold on a POS basis due to adopting the new revenue recognition guidance in the first interim period of adoption. We expect this favorable impact will be largely offset during the three quarters following the initial adoption. The impact for the second quarter of 2018 was in line with these expectations. We continue to expect the adoption of the new revenue recognition guidance will have less than a $10.0 million impact on POS revenue in the aggregate for 2018. Revenue from any tickets sold under these arrangements that were in the lottery distribution channel at December 31, 2017 will not be recognized as retail sales occur, as both the revenue value of such tickets and the historical cost of such inventory at December 31, 2017 was reflected directly into shareholders’ deficit at adoption. The adoption of ASC 606 related to inventory in the distribution channel at December 31, 2017 resulted in an increase to contract assets (included in Prepaid expenses, deposits and other current assets) totaling $52.0 million, a reduction to inventory totaling $33.0 million and a decrease to accumulated net loss totaling $19.0 million. The impact of ASC 606 on our June 30, 2018 consolidated balance sheet was a $39.5 million decrease to inventories and a $45.4 million increase to contract assets included in Prepaid expenses, deposits and other current assets. Lottery Systems Our Lottery business segment offers our customers a number of related, value-added services as part of an integrated product offering. These services include lottery systems, including point-of-sale terminals and other equipment, software, data communication services and support and instant game validation systems, and software, hardware and related services for sports wagering and keno systems. For our integrated lottery systems service contracts (described above), our single performance obligation is a promise to perform a series of stand-ready services to operate a fully-functional draw lottery. Revenue is recognized over time in an amount generally based on a percentage of sales of the related games, which represents our measure of progress toward satisfying our performance obligation. For our perpetual licensing of customized lottery software contracts, we generally recognize revenue over time using costs incurred to date relative to total estimated completion costs to measure progress toward satisfying our performance obligations, which we believe best depicts the transfer of control to the customer. Maintenance on lottery software and lottery terminals is considered a stand-ready obligation, with control transferring and revenue being recognized over time ratably over the maintenance and support period. If a lottery systems contract includes multiple promised goods and services, these contracts are accounted for as described in the "Contracts with Customers with Multiple Promised Goods and Services" section above. Social Gaming Social gaming revenues are generated from the sale of virtual coins, chips or bingo cards (collectively referred to as "virtual currency"), which players can use to play casino-style slot and table games or bingo games (i.e., spin in the case of slot games, bet in the case of table games and use of bingo cards in the case of bingo games). Control transfers and we recognize revenues from player purchases of virtual currency as the virtual currency is consumed for game play, which is based on a historical data analysis. Because we have control over the content and functionality of games before they are accessed by the end user, we have determined we are the principal and, as a result, revenues are recorded on a gross basis. Payment processing fees paid to platform providers (such as Facebook, Apple, Amazon and Google) on a revenue participation basis are recorded within cost of services. Digital Digital revenue is generated from professional services related to highly customized software design, development, licensing, maintenance and support services associated with a comprehensive suite of technology solutions, including sports books and betting markets across both fixed-odds and pari-mutuel betting styles. Additionally, through our integrated suite of various platform and technology solutions, we provide gaming operators optional portals for reporting and administrative functions, and access to a wide portfolio of content, including casino, lottery and bingo style games. Determination of performance obligations and timing of the transfer of control vary based on the nature of the contract. Generally, these contracts contain multiple promises, including the following: (i) implementation of customized software solution and the associated software license; (ii) support services and unspecified software updates; (iii) professional development services; and (iv) access to the game content. Generally control transfers and we recognize revenue from the implementation of a customized software solution and the associated software license over time using costs incurred to date relative to total estimated completion costs to measure progress toward satisfying our performance obligations, which we believe best depicts the transfer of control to the customer. Support services and unspecified software updates are considered stand-ready obligations, therefore control transfers and revenue is recognized over time ratably over the term of the support period. Professional development services generally relate to post-go live development, and control transfers and revenue is recognized over time as services are rendered. We also generate revenue from various content aggregation platforms, remote gaming servers, our SG Universe^® platform and various other platforms, which deliver a wide spectrum of internally developed and branded games and popular third-party provided games to gaming operators. We provide daily access to these platforms and are typically compensated based on variable consideration, such as a percentage of net gaming revenue with variability generally resolved in the reporting period. All Digital revenue is classified as services revenue.