Regulatory Matters - Schedule of Regulatory Capital Amounts and Ratios of Company and Bank (Details)	9 Months Ended
	Sep. 30, 2017
Regulatory matters
Minimum Capital Conservation Buffer (as percent)	1.25%
Annual increase in minimum Capital Conservation Buffer (as percent)	0.625%
Increased Capital Conservation Buffer (as percent)	2.50%
Common Tier 1, Risk-based, Capital ratios (as a percent)	10.00%
Common Tier 1, Risk-based, Well-capitalized requirement (as a percent)	6.50%
Common Tier 1, Risk-based, Minimum capital requirement (as a percent)	7.00%
Tier I, Risk-based, Capital ratios (as a percent)	11.60%
Tier I, Risk-based, Well-capitalized requirement (as a percent)	8.00%
Tier I, Risk-based, Minimum capital requirement (as a percent)	8.50%
Total capital, Risk-based, Capital ratios (as a percent)	14.50%
Total capital, Risk-based, Well-capitalized requirement (as a percent)	10.00%
Total capital, Risk-based, Minimum capital requirement (as a percent)	10.50%
Tier I, Leverage, Capital ratios (as a percent)	10.00%
Tier I, Leverage, Well-capitalized requirement (as a percent)	5.00%
Tier I, Leverage, Minimum capital requirement (as a percent)	4.00%
Bank
Regulatory matters
Common Tier 1, Risk-based, Capital ratios (as a percent)	12.00%
Tier I, Risk-based, Capital ratios (as a percent)	12.00%
Total capital, Risk-based, Capital ratios (as a percent)	13.10%
Tier I, Leverage, Capital ratios (as a percent)	10.40%