Securities Sold Under Repurchase Agreements - Summary of Information Concerning Securities Sold Under Repurchase Agreements (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Investments Debt And Equity Securities [Abstract]
Average daily balance during the year	$ 526,000	$ 6,489,000
Average interest rate during the year	0.15%	0.23%
Maximum month-end balance during the year	$ 3,316,000	$ 15,862,000
Weighted average interest rate at year-end		0.25%