Securities (Unrealized Loss NOT deemed to be OTTI) (Details) $ in Thousands	Sep. 30, 2017 USD ($) holding	Dec. 31, 2016 USD ($) holding
Summary of gross unrealized losses and fair value of investments
No of holdings | holding	77	121
Fair value, less than 12 months	$ 281,477	$ 444,471
Unrealized loss position for available for sale and held to maturity securities in a continuous loss position for less than 12 months	(2,886)	(5,510)
Fair value, 12 months or longer	62,409	56,356
Unrealized loss position for available for sale and held to maturity securities in a continuous loss position for more than 12 months	(2,654)	(3,084)
Fair value, Total	343,886	500,827
Available for Sale and Held to Maturity Securities Continuous Unrealized Loss Position Aggregate Loss	$ (5,540)	$ (8,594)
Agency mortgage-backed securities
Summary of gross unrealized losses and fair value of investments
No of holdings | holding	23	57
Fair value, less than 12 months	$ 88,083	$ 137,949
Unrealized loss position for available for sale and held to maturity securities in a continuous loss position for less than 12 months	(438)	(1,594)
Fair value, 12 months or longer	762	0
Unrealized loss position for available for sale and held to maturity securities in a continuous loss position for more than 12 months	(7)	0
Fair value, Total	88,845	137,949
Available for Sale and Held to Maturity Securities Continuous Unrealized Loss Position Aggregate Loss	$ (445)	$ (1,594)
Agency Collateralized Mortgage Obligations [Member]
Summary of gross unrealized losses and fair value of investments
No of holdings | holding	25	32
Fair value, less than 12 months	$ 145,572	$ 243,051
Unrealized loss position for available for sale and held to maturity securities in a continuous loss position for less than 12 months	(2,278)	(3,140)
Fair value, 12 months or longer	52,466	47,403
Unrealized loss position for available for sale and held to maturity securities in a continuous loss position for more than 12 months	(1,707)	(1,989)
Fair value, Total	198,038	290,454
Available for Sale and Held to Maturity Securities Continuous Unrealized Loss Position Aggregate Loss	$ (3,985)	$ (5,129)
Single issuer trust preferred securities issued by banks and insurers
Summary of gross unrealized losses and fair value of investments
No of holdings | holding		1
Fair value, less than 12 months		$ 0
Unrealized loss position for available for sale and held to maturity securities in a continuous loss position for less than 12 months		0
Fair value, 12 months or longer		1,036
Unrealized loss position for available for sale and held to maturity securities in a continuous loss position for more than 12 months		(3)
Fair value, Total		1,036
Available for Sale and Held to Maturity Securities Continuous Unrealized Loss Position Aggregate Loss		$ (3)
Pooled trust preferred securities issued by banks and insurers
Summary of gross unrealized losses and fair value of investments
No of holdings | holding	1	1
Fair value, less than 12 months	$ 0	$ 0
Unrealized loss position for available for sale and held to maturity securities in a continuous loss position for less than 12 months	0	0
Fair value, 12 months or longer	1,624	1,583
Unrealized loss position for available for sale and held to maturity securities in a continuous loss position for more than 12 months	(558)	(616)
Fair value, Total	1,624	1,583
Available for Sale and Held to Maturity Securities Continuous Unrealized Loss Position Aggregate Loss	$ (558)	$ (616)
Equity securities
Summary of gross unrealized losses and fair value of investments
No of holdings | holding	24	25
Fair value, less than 12 months	$ 897	$ 3,625
Unrealized loss position for available for sale and held to maturity securities in a continuous loss position for less than 12 months	(17)	(77)
Fair value, 12 months or longer	7,557	6,334
Unrealized loss position for available for sale and held to maturity securities in a continuous loss position for more than 12 months	(382)	(476)
Fair value, Total	8,454	9,959
Available for Sale and Held to Maturity Securities Continuous Unrealized Loss Position Aggregate Loss	$ (399)	$ (553)
Small Business Administration Pooled Securities [Member]
Summary of gross unrealized losses and fair value of investments
No of holdings | holding	4	5
Fair value, less than 12 months	$ 46,925	$ 59,846
Unrealized loss position for available for sale and held to maturity securities in a continuous loss position for less than 12 months	(153)	(699)
Fair value, 12 months or longer	0	0
Unrealized loss position for available for sale and held to maturity securities in a continuous loss position for more than 12 months	0	0
Fair value, Total	46,925	59,846
Available for Sale and Held to Maturity Securities Continuous Unrealized Loss Position Aggregate Loss	$ (153)	$ (699)