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Corporate Indebtedness - Additional Information (Details) | 9 Months Ended |
--- | --- | ---
Sep. 30, 2018 USD ($) extension | Dec. 31, 2017 USD ($)
Corporate Indebtedness |  |
Outstanding under line of credit facility | $ 136,734,000 | $ 30,336,000
Term Loan B, Maturity November 21, 2024 | Term loan |  |
Corporate Indebtedness |  |
Credit facility, maximum borrowing capacity | $ 200,000,000 |
Term Loan B, Maturity November 21, 2024 | LIBOR | Term loan |  |
Corporate Indebtedness |  |
Interest rate added to base rate (as a percent) | 1.65% |
Term Loan B, Maturity November 21, 2024 | LIBOR | Minimum | Term loan |  |
Corporate Indebtedness |  |
Interest rate added to base rate (as a percent) | 1.50% |
Term Loan B, Maturity November 21, 2024 | LIBOR | Maximum | Term loan |  |
Corporate Indebtedness |  |
Interest rate added to base rate (as a percent) | 2.45% |
Revolving credit facility |  |
Corporate Indebtedness |  |
Facility fee (as a percent) | 0.20% |
Outstanding under line of credit facility | $ 145,000,000 |
Revolving credit facility | Minimum |  |
Corporate Indebtedness |  |
Facility fee (as a percent) | 0.125% |
Revolving credit facility | Maximum |  |
Corporate Indebtedness |  |
Facility fee (as a percent) | 0.30% |
Term loan |  |
Corporate Indebtedness |  |
Credit facility, maximum borrowing capacity | $ 1,500,000,000 |
Term loan | Line of Credit |  |
Corporate Indebtedness |  |
Long-term debt, carrying value | 1,500,000,000 | 1,500,000,000
2012 Credit Facility |  |
Corporate Indebtedness |  |
Letters of credit | 11,800,000 |
Ability to borrow under line of credit facility | 1,300,000,000 |
2012 Credit Facility | Line of Credit |  |
Corporate Indebtedness |  |
Long-term debt, carrying value | 136,700,000 | $ 30,300,000
Term Loan A, Maturity March 31, 2023 | Term loan |  |
Corporate Indebtedness |  |
Credit facility, maximum borrowing capacity | $ 1,300,000,000.0 |
Term Loan A, Maturity March 31, 2023 | LIBOR | Term loan |  |
Corporate Indebtedness |  |
Interest rate added to base rate (as a percent) | 1.10% |
Term Loan A, Maturity March 31, 2023 | LIBOR | Minimum | Term loan |  |
Corporate Indebtedness |  |
Interest rate added to base rate (as a percent) | 0.90% |
Term Loan A, Maturity March 31, 2023 | LIBOR | Maximum | Term loan |  |
Corporate Indebtedness |  |
Interest rate added to base rate (as a percent) | 1.75% |
Revolving credit facility | Revolving Credit Facility, Maturity March 31, 2022 | Line of Credit |  |
Corporate Indebtedness |  |
Credit facility, maximum borrowing capacity | $ 1,500,000,000.0 |
Number of extensions | extension | 2 |
Term of extension | 6 months |
Maximum borrowing capacity, optional expansion | $ 4,500,000,000.0 |
Revolving credit facility | Revolving Credit Facility, Maturity March 31, 2022 | LIBOR | Line of Credit |  |
Corporate Indebtedness |  |
Interest rate added to base rate (as a percent) | 1.00% |
Revolving credit facility | Revolving Credit Facility, Maturity March 31, 2022 | LIBOR | Minimum | Line of Credit |  |
Corporate Indebtedness |  |
Interest rate added to base rate (as a percent) | 0.825% |
Revolving credit facility | Revolving Credit Facility, Maturity March 31, 2022 | LIBOR | Maximum | Line of Credit |  |
Corporate Indebtedness |  |
Interest rate added to base rate (as a percent) | 1.55% |

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- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
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- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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- Definition The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used. + References No definition available. + Details
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- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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