Borrowings - Subordinated Debt (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2003 USD ($) trust
Debt Instrument [Line Items]
Net proceeds from sale of common stock	$ 1,196	$ 153,356	$ 116,054
Junior Subordinated Debentures
Debt Instrument [Line Items]
Number of separate trusts | trust				2
Preferred securities issued to form the trust				$ 30,000
Junior Subordinated Debentures | Floating Rate Trust Preferred Securities Trust I
Debt Instrument [Line Items]
Preferred securities issued to form the trust				9,000
Proceeds from issuance of debt				9,280
Net proceeds from sale of common stock				280
Debt instrument, interest rate	5.65%	4.59%
Junior Subordinated Debentures | Floating Rate Trust Preferred Securities Trust I | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	3.25%
Junior Subordinated Debentures | Floating Rate Trust Preferred Securities Trust II
Debt Instrument [Line Items]
Preferred securities issued to form the trust				21,000
Proceeds from issuance of debt				21,650
Net proceeds from sale of common stock				$ 650
Debt instrument, interest rate	5.97%	4.82%
Junior Subordinated Debentures | Floating Rate Trust Preferred Securities Trust II | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	3.15%