Commitments and Contingencies - Schedule of Senior Unsecured Notes (Parenthetical) (Detail) |
Jun. 30, 2019 |
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5.25% Senior Unsecured Notes Due 2024 [Member] | |
Debt Instrument [Line Items] | |
Debt instrument interest rate | 5.25% |
5.75% Senior Unsecured Notes Due 2025 [Member] | |
Debt Instrument [Line Items] | |
Debt instrument interest rate | 5.75% |
4.75% Senior Unsecured Notes Due 2026 [Member] | |
Debt Instrument [Line Items] | |
Debt instrument interest rate | 4.75% |
5.375% Senior Unsecured Notes Due 2027 [Member] | |
Debt Instrument [Line Items] | |
Debt instrument interest rate | 5.375% |