Approximate annual revenues reported by the acquiree company.

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The acquisition price to be paid in addition to the tangible book value of the acquiree at the closing date.

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Percentage of investment acquired by members or limited partners of limited liability company (LLC).

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The recovery percentage of the entity's surety bond claim losses that its joint venture partner is obligated to pay.

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The amount of total assets using prescribed or permitted statutory accounting practices (rather than GAAP, if different) of the state or country.

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Number of persons employed by the Entity

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Percentage of voting equity interests acquired at the acquisition date in the business combination.

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-Name Accounting Standards Codification
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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Percentage investment held by the managing member or general partner of the limited liability company (LLC) or limited partnership (LP).

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-Name Accounting Standards Codification
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Percentage investment held by members or limited partners of limited liability company (LLC) or limited partnership (LP).

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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.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Represents the number of stores.

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No definition available.

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Description of the nature and terms of commitment.

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No definition available.

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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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The amount of statutory capital and surplus (stockholders' equity) as of the balance sheet date using prescribed or permitted statutory accounting practices (rather than GAAP, if different) of the state or country.

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Contingencies and Commitments - Narrative (Detail)			3 Months Ended	9 Months Ended
Contingencies and Commitments - Narrative (Detail)	Oct. 03, 2017 USD ($) Employee Location	Jul. 07, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)
NICO [Member] \| Purchase Agreement [Member] \| Medical Liability Mutual Insurance Company [Member]
Contingencies and Commitments [Line Items]
Statutory assets					$ 5,500,000,000
Statutory policyholders' surplus					$ 2,100,000,000
Acquisition price in addition to tangible book value of acquiree			$ 100,000,000
Berkadia Commercial Mortgage (investee) [Member]
Contingencies and Commitments [Line Items]
Voting interest in investee				50.00%
Berkadia Commercial Mortgage (investee) [Member] \| Commercial Paper [Member]
Contingencies and Commitments [Line Items]
Maximum outstanding balance of commercial paper borrowings				$ 1,500,000,000
Leucadia National Corporation (venture partner) [Member] \| Berkadia Commercial Mortgage (investee) [Member]
Contingencies and Commitments [Line Items]
Voting interest in investee				50.00%
Leucadia National Corporation (venture partner) [Member] \| Berkadia Commercial Mortgage (investee) [Member] \| Insurance Group [Member]
Contingencies and Commitments [Line Items]
Reimbursement rate from joint venture partner of Company's surety bond claim losses				50.00%
Energy Future Holdings Corp. [Member] \| Berkshire Hathaway Energy [Member] \| Purchase Agreement [Member] \| Oncor Electric Delivery Company LLC [Member]
Contingencies and Commitments [Line Items]
Percentage of outstanding equity interests to be acquired		80.03%
Consideration for business acquisition		$ 9,000,000,000
Agreement termination, description				In August 2017, the agreement to acquire Oncor was terminated by EFH.
Subsequent Event [Member] \| Investment Agreement and Equity Purchase Agreement [Member] \| Pilot Travel Centers LLC, , d/b/a Pilot Flying J [Member]
Contingencies and Commitments [Line Items]
Number of locations \| Location	750
Annual revenues	$ 20,000,000,000
Subsequent Event [Member] \| Haslam Family [Member] \| Investment Agreement and Equity Purchase Agreement [Member] \| Pilot Travel Centers LLC, , d/b/a Pilot Flying J [Member]
Contingencies and Commitments [Line Items]
Majority ownership percentage	50.10%
Subsequent Event [Member] \| Haslam Family [Member] \| Agreement to Acquire Additional Interest in 2023 [Member] \| Pilot Travel Centers LLC, , d/b/a Pilot Flying J [Member]
Contingencies and Commitments [Line Items]
Ownership percentage	20.00%
Subsequent Event [Member] \| Third Party [Member] \| Investment Agreement and Equity Purchase Agreement [Member] \| Pilot Travel Centers LLC, , d/b/a Pilot Flying J [Member]
Contingencies and Commitments [Line Items]
Ownership percentage	11.30%
Subsequent Event [Member] \| Minimum [Member] \| Investment Agreement and Equity Purchase Agreement [Member] \| Pilot Travel Centers LLC, , d/b/a Pilot Flying J [Member]
Contingencies and Commitments [Line Items]
Number of team members \| Employee	27,000
Subsequent Event [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Investment Agreement and Equity Purchase Agreement [Member] \| Pilot Travel Centers LLC, , d/b/a Pilot Flying J [Member]
Contingencies and Commitments [Line Items]
Ownership percentage	38.60%
Subsequent Event [Member] \| Berkshire Hathaway Inc. (Parent) [Member] \| Agreement to Acquire Additional Interest in 2023 [Member] \| Pilot Travel Centers LLC, , d/b/a Pilot Flying J [Member]
Contingencies and Commitments [Line Items]
Percentage of additional interest to be acquired	41.40%