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Securities Held-to-Maturity - Additional Information (Detail) - Securities	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Number of securities determined to be other than temporarily impaired	0	0

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- Definition

Number of securities determined to be other than temporarily impaired.

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