Bank subsidiary (Details 6) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Amortized Cost
Due in one year or less	$ 28,120
Due after one year through five years	34,885
Due after five years through ten years	89,055
Due after ten years	25,358
Total amortized cost	177,418
Mortgage-related securities-FNMA, FHLMC and GNMA - amortized cost	381,281
Total available-for-sale securities, amortized cost	558,699	653,492
Fair value
Due in one year or less	28,192
Due after one year through five years	35,220
Due after five years through ten years	90,477
Due after ten years	24,239
Total fair value	178,128
Mortgage-related securities-FNMA, FHLMC and GNMA - fair value	382,044
Total available for sale securities	$ 560,172	$ 671,358