Investment Securities (Unrealized Gain (Loss) on Investments) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Net Investment Income [Line Items]
Amortized cost	$ 518,475	$ 307,648
Gross unrealized gains	5,259	4,108
Gross unrealized losses	(459)	(1,494)
Estimated fair value	523,275	310,262
Amortized cost	141,326	139,424
Gross unrealized gains	6,889	2,843
Gross unrealized losses	(2)	(7)
Estimated fair value	148,213	142,260
U.S. Agency mortgage-backed securities (MBS)
Net Investment Income [Line Items]
Amortized cost	168,862	154,691
Gross unrealized gains	2,715	2,698
Gross unrealized losses	(81)	(455)
Estimated fair value	171,496	156,934
Amortized cost	102,226	98,800
Gross unrealized gains	4,816	1,875
Gross unrealized losses	(2)	(5)
Estimated fair value	107,040	100,670
Non-agency MBS
Net Investment Income [Line Items]
Amortized cost	269,508	118,765
Gross unrealized gains	1,540	477
Gross unrealized losses	(296)	(1,016)
Estimated fair value	270,752	118,226
U.S. Agency asset-backed securities
Net Investment Income [Line Items]
Amortized cost	6,876	7,468
Gross unrealized gains	605	800
Gross unrealized losses	(52)	(23)
Estimated fair value	7,429	8,245
Corporate securities
Net Investment Income [Line Items]
Amortized cost	72,695	26,199
Gross unrealized gains	382	121
Gross unrealized losses	(30)	0
Estimated fair value	73,047	26,320
Mutual fund
Net Investment Income [Line Items]
Amortized cost	534	525
Gross unrealized gains	17	12
Gross unrealized losses	0	0
Estimated fair value	551	537
Obligations of state and political subdivisions
Net Investment Income [Line Items]
Amortized cost	38,810	421
Gross unrealized gains	2,073	0
Gross unrealized losses	0	0
Estimated fair value	40,883	421
Tax credit investments
Net Investment Income [Line Items]
Amortized cost	290	40,203
Gross unrealized gains	0	968
Gross unrealized losses	0	(2)
Estimated fair value	$ 290	$ 41,169