Interest coverage ratio required in two years and each quarter thereafter.

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Leverage ratio required each quarter thereafter.

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Maximum percentage of stock of certain first-tier foreign subsidiaries pledged to secure senior credit facility.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

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Amount of the required periodic payment applied to principal.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

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Long-Term Debt and Financing Arrangements - Additional Information (Details)	3 Months Ended		9 Months Ended	18 Months Ended
	Dec. 31, 2019 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
Maximum percentage of stock of certain first-tier foreign subsidiaries pledged to secure senior credit facility		66.00%
Debt outstanding		$ 1,406,000,000			$ 1,294,000,000
Leverage Ratio Required (Maximum) for future quarters		3.50
Interest coverage ratio (minimum)		2.75
5.375% Senior Notes Due 2024
Debt Instrument [Line Items]
Outstanding debt		$ 225,000,000
Debt issuance costs		4,000,000
Debt outstanding		$ 221,000,000
Stated percentage		5.375%
5% Senior Notes Due July 15 2026
Debt Instrument [Line Items]
Outstanding debt		$ 500,000,000
Debt issuance costs		8,000,000
Debt outstanding		$ 492,000,000
Stated percentage		5.00%
Other Debt
Debt Instrument [Line Items]
Unsecured debt		$ 126,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		1,200,000,000
Outstanding debt		417,000,000
Unused borrowing capacity		783,000,000
Revolving Credit Facility \| Tranche Term Facility
Debt Instrument [Line Items]
Outstanding debt		264,000,000
Debt issuance costs		1,000,000
Debt outstanding		263,000,000
Principal payments excluded from current liabilities		24,000,000
Revolving Credit Facility \| Term loan
Debt Instrument [Line Items]
Outstanding debt		264,000,000
Letter of Credit
Debt Instrument [Line Items]
Outstanding debt		$ 0
Future payment \| Revolving Credit Facility \| Tranche Term Facility
Debt Instrument [Line Items]
Repayment of term loan	$ 195,000,000		$ 5,625,000	$ 7,500,000