Allowance for Loan Losses - (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Allowance For Loan And Lease Losses [Line Items]
Provision (recoupment) for loan losses			$ 17,076	$ 3,311
Non ASC 310-30 [Member]
Allowance For Loan And Lease Losses [Line Items]
Charge-offs, net	$ 3,500	$ 500	4,000	700
Provision (recoupment) for loan losses	6,400	1,850	17,881	3,253
Non ASC 310-30 [Member] | Energy Loans [Member]
Allowance For Loan And Lease Losses [Line Items]
Provision (recoupment) for loan losses	4,300		15,000
ASC 310-30 [Member]
Allowance For Loan And Lease Losses [Line Items]
Provision (recoupment) for loan losses	$ 57	$ 8	$ (805)	$ 58