Derivative Financial Instruments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Effective portion of gain (loss) on derivative	$ 100,000,000
Cross Currency Interest Rate Swap Effective Period of Swap December Twenty Three Two Thousand Sixteen To December Thirty One Two Thousand Nineteen [Member]
Derivative [Line Items]
Notional Amount	100,000,000
Cross Currency Interest Rate Swap Effective Period of Swap December Twenty Three Two Thousand Sixteen To December Thirty One Two Thousand Eighteen and December Twenty Three Two Thousand Sixteen To June Thirty Two Thousand Seventeen [Member]
Derivative [Line Items]
Notional Amount	70,000,000
Cross Currency Interest Rate Swap Effective Period of Swap June Thirty Two Thousand Seventeen To December Thirty One Two Thousand Seventeen [Member]
Derivative [Line Items]
Notional Amount	30,000,000
Cross Currency Interest Rate Swap Effective Period of Swap December Twenty Three Two Thousand Sixteen To December Thirty One Two Thousand Eighteen [Member]
Derivative [Line Items]
Notional Amount	40,000,000
Derivatives outstanding amount	30,000,000
Interest Rate Swaps [Member]
Derivative [Line Items]
Unrealized gain(loss) related to interest rate swaps in accumulated other comprehensive loss	$ 200,000	$ (700,000)