Financial Instruments and Risk - Additional Information (Detail)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Schedule Of Cost Method Investments [Line Items]
Average days to maturity of Company's portfolio of cash equivalents and marketable securities	45 days	61 days
Maximum [Member]
Schedule Of Cost Method Investments [Line Items]
Maturity period of securities	1 year

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.

No definition available.

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration