Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended
Dec. 31, 2014 item	Dec. 31, 2013	Dec. 31, 2012
Summary of Significant Accounting Policies
Minimum number of locations in which company operates metal service network	300
Number of states in which the company operates metal service center network	39
Number of countries in which entity operates	12
Minimum number of metal products distributes by the company	100,000
Fair Values of Financial Instruments
Carrying value, before deducting unamortized discount or premiums	$ 2,319,100,000us-gaap_DebtInstrumentCarryingAmount	$ 2,112,300,000us-gaap_DebtInstrumentCarryingAmount
Carrying value	2,319,100,000us-gaap_LongTermDebt
Goodwill Policy
Number of operating segments	1us-gaap_NumberOfOperatingSegments
Number of reportable segments	1us-gaap_NumberOfReportableSegments
Impairment of goodwill	0us-gaap_GoodwillImpairmentLoss	0us-gaap_GoodwillImpairmentLoss	0us-gaap_GoodwillImpairmentLoss
Tradename
Impairment of intangible assets	0	14,900,000	2,500,000
Senior Unsecured Notes - Publicly Traded
Fair Values of Financial Instruments
Carrying value, before deducting unamortized discount or premiums	1,100,000,000
Fair value	1,160,000,000	1,140,000,000
Carrying value	$ 1,100,000,000

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Represents the minimum number of metal products distributed by entity.

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The minimum number of locations the entity operates in as of the balance sheet date.

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Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of impairment loss resulting from write-down of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit to fair value.

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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The number of countries in which the entity operates as of balance sheet date.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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The number of states the entity operates in as of the balance sheet date.

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