Employee Benefit Plans - Options Outstanding by Exercise Price Range (Details) - Officer and Employee Plans [Member] - $ / shares	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 11.77	$ 10.57	$ 10.62
Number Outstanding (in shares)	213,086	717,524	817,414
Options Outstanding, Weighted Average Remaining Life	4 years 10 months 24 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 11.77
Options, Number Exercisable (in shares)	174,445
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 11.05
6.60 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 6.60
Number Outstanding (in shares)	39,000
Options Outstanding, Weighted Average Remaining Life	4 years 8 months 12 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 6.60
Options, Number Exercisable (in shares)	39,000
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 6.60
6.80 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 6.80
Number Outstanding (in shares)	17,625
Options Outstanding, Weighted Average Remaining Life	3 years 8 months 12 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 6.80
Options, Number Exercisable (in shares)	17,625
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 6.80
9.48 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 9.48
Number Outstanding (in shares)	27,375
Options Outstanding, Weighted Average Remaining Life	5 years 8 months 12 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 9.48
Options, Number Exercisable (in shares)	27,375
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 9.48
9.60 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 9.60
Number Outstanding (in shares)	35,625
Options Outstanding, Weighted Average Remaining Life	6 years 8 months 12 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 9.60
Options, Number Exercisable (in shares)	35,625
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 9.60
10.48 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 10.48
Number Outstanding (in shares)	20,245
Options Outstanding, Weighted Average Remaining Life	2 months 12 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 10.48
Options, Number Exercisable (in shares)	20,245
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 10.48
11.67 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 11.67
Number Outstanding (in shares)	3,250
Options Outstanding, Weighted Average Remaining Life	3 years 7 months 6 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 11.67
Options, Number Exercisable (in shares)	3,250
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 11.67
14.40 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 14.40
Number Outstanding (in shares)	13,305
Options Outstanding, Weighted Average Remaining Life	1 year 8 months 12 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 14.40
Options, Number Exercisable (in shares)	13,305
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 14.40
15.05 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 15.05
Number Outstanding (in shares)	42,745
Options Outstanding, Weighted Average Remaining Life	8 years 3 months 18 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 15.05
Options, Number Exercisable (in shares)	4,104
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 15.05
31.96 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 31.96
Number Outstanding (in shares)	13,916
Options Outstanding, Weighted Average Remaining Life	8 months 12 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 31.96
Options, Number Exercisable (in shares)	13,916
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 31.96