Commitments and Contingencies (Schedule of Total Unfunded Commitments) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Commitment And Contingencies [Line Items]
Total unfunded commitments	$ 795,059	$ 687,946
Commitments to fund loans [Member]
Commitment And Contingencies [Line Items]
Total unfunded commitments	235,078	181,904
Unfunded Commitment Line Of Credit [Member]
Commitment And Contingencies [Line Items]
Total unfunded commitments	551,838	498,857
Commercial And Standby Letters Of Credit [Member]
Commitment And Contingencies [Line Items]
Total unfunded commitments	$ 8,143	$ 7,185