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Long-Term Debt - Summary of Interest Received and Paid under Term of Cash Flow Swap (Detail) | 12 Months Ended
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Dec. 31, 2017 USD ($)
Derivatives, Fair Value [Line Items] |
Receive Rate | one-month LIBOR
Cash Flow Swap [Member] |
Derivatives, Fair Value [Line Items] |
Notional Amount | $ 250,000,000
Pay Rate | 1.887%
Receive Rate | one-month LIBOR
Maturing Date | Jun. 30, 2018
Cash Flow Swap 1 [Member] |
Derivatives, Fair Value [Line Items] |
Notional Amount | $ 125,000,000
Pay Rate | 1.90%
Receive Rate | one-month LIBOR
Maturing Date | Jul. 01, 2018
Cash Flow Swap 2 [Member] |
Derivatives, Fair Value [Line Items] |
Notional Amount | $ 50,000,000
Pay Rate | 2.32%
Receive Rate | one-month LIBOR
Maturing Date | Jul. 01, 2019
Cash Flow Swap 3 [Member] |
Derivatives, Fair Value [Line Items] |
Notional Amount | $ 200,000,000
Pay Rate | 2.313%
Receive Rate | one-month LIBOR
Maturing Date | Jul. 01, 2019
Cash Flow Swap 4 [Member] |
Derivatives, Fair Value [Line Items] |
Notional Amount | $ 100,000,000
Pay Rate | 1.384%
Receive Rate | one-month LIBOR
Maturing Date | Jul. 01, 2020
Cash Flow Swap 5 [Member] |
Derivatives, Fair Value [Line Items] |
Notional Amount | $ 125,000,000
Pay Rate | 1.158%
Receive Rate | one-month LIBOR
Maturing Date | Jul. 01, 2019
Cash Flow Swap 6 [Member] |
Derivatives, Fair Value [Line Items] |
Notional Amount | $ 150,000,000
Pay Rate | 1.31%
Receive Rate | one-month LIBOR
Maturing Date | Jul. 01, 2020
Cash Flow Swap 7 [Member] |
Derivatives, Fair Value [Line Items] |
Notional Amount | $ 125,000,000
Pay Rate | 1.02%
Receive Rate | one-month LIBOR
Maturing Date | Jul. 01, 2018
Cash Flow Swap 8 [Member] |
Derivatives, Fair Value [Line Items] |
Notional Amount | $ 62,500,000
Pay Rate | 2.00%
Receive Rate | one-month LIBOR
Maturing Date | Jul. 01, 2021
Cash Flow Swap 9 [Member] |
Derivatives, Fair Value [Line Items] |
Notional Amount | $ 62,500,000
Pay Rate | 2.00%
Receive Rate | one-month LIBOR
Maturing Date | Jul. 01, 2021
Cash Flow Swap 10 [Member] |
Derivatives, Fair Value [Line Items] |
Notional Amount | $ 62,500,000
Pay Rate | 2.00%
Receive Rate | one-month LIBOR
Maturing Date | Jul. 01, 2021
Cash Flow Swap 11 [Member] |
Derivatives, Fair Value [Line Items] |
Notional Amount | $ 62,500,000
Pay Rate | 2.00%
Receive Rate | one-month LIBOR
Maturing Date | Jul. 01, 2021

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