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Fair Value Measurements - Reconciliation of the Beginning and Ending Balances for Derivative Instruments Classified as Level 3 in the Fair Value Hierarchy (Parenthetical) (Detail) - Fair Value, Inputs, Level 3 $ in Thousands | 3 Months Ended
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Mar. 31, 2018 USD ($)
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items] |  |
Transfer out of Level 3 | $ 2,142 | [1]
Swaptions |  |
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items] |  |
Transfer out of Level 3 | $ 2,100 |
[1] | During first quarter 2018, we transferred $2.1 million of swaption contracts out of Level 3 resulting from the exercise of our Level 3 swaptions by the counterparties.

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- Definition 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. + References No definition available. + Details
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- Definition Amount of transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy. + References No definition available. + Details
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- Details
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