Junior Subordinated Debt Owed to Unconsolidated Trusts (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Junior subordinated debt owed to unconsolidated trusts
Junior subordinated debt owed to unconsolidated trusts	$ 71,081	$ 71,008
Trust Preferred Securities
Junior subordinated debt owed to unconsolidated trusts
Percentage limit on inclusion of qualifying trust preferred securities in Tier I Capital	25.00%
Trust preferred securities qualified as Tier I capital (as a percent)	100.00%
Maximum of holding companies assets retained	$ 15,000,000
Junior Subordinated Notes | Trust Preferred Securities
Junior subordinated debt owed to unconsolidated trusts
Maximum period to defer payment of interest on the notes and, therefore, distributions on the trust preferred securities	5 years
Parent
Junior subordinated debt owed to unconsolidated trusts
Junior subordinated debt owed to unconsolidated trusts	$ 71,100	$ 71,000