Deposits (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Deposits Abstract
Certificates of deposit	$ 1,159,285	$ 1,237,140	$ 1,300,580
Interest-bearing demand deposits	3,260,482	2,927,820	2,900,140
Non-interest bearing demand deposits	1,927,309	1,639,953	1,654,308
Savings deposits	726,373	655,132	658,903
Other time deposits	4,560	1,000	4,297
Total deposits	$ 7,078,009	$ 6,461,045	$ 6,518,228