Securities Available-for-Sale - Narrative (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) security	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Carrying value of securities available-for-sale | $	$ 108,800,000	$ 101,000,000
Proceeds from sale of securities available-for-sale | $	44,582,000	51,148,000	$ 11,975,000
Gross realized gains on sales of securities available-for-sale | $	493,000	60,000	382,000
Gross realized losses on sales of securities available-for-sale | $	187,000	3,000	0
Impairment charges against earnings | $	0	0	0
Gains on trading securities | $	$ 507,000
Losses on trading securities | $		$ 396,000	$ 155,000
Continuous Unrealized Loss Position Less Than 12 Months | REMIC
Schedule of Available-for-sale Securities [Line Items]
Number of securities | security	10
GSE | Continuous Unrealized Loss Position 12 Months Or Longer
Schedule of Available-for-sale Securities [Line Items]
Number of securities | security	19
GSE | Continuous Unrealized Loss Position 12 Months Or Longer | REMIC
Schedule of Available-for-sale Securities [Line Items]
Number of securities | security	9
GSE | Continuous Unrealized Loss Position Less Than 12 Months | Pass-through certificates
Schedule of Available-for-sale Securities [Line Items]
Number of securities | security	22
Non-GSE | Continuous Unrealized Loss Position 12 Months Or Longer | REMIC
Schedule of Available-for-sale Securities [Line Items]
Number of securities | security	2
Corporate bonds | Continuous Unrealized Loss Position Less Than 12 Months | REMIC
Schedule of Available-for-sale Securities [Line Items]
Number of securities | security	5
Municipal bonds | Continuous Unrealized Loss Position Less Than 12 Months | REMIC
Schedule of Available-for-sale Securities [Line Items]
Number of securities | security	2