Bank segment - Contractual maturities of securities (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Amortized Cost
Due in one year or less	$ 0
Due after one year through five years	75,332
Due after five years through ten years	71,667
Due after ten years	62,026
Total amortized cost	209,025
Mortgage-related securities-FNMA, FHLMC and GNMA - amortized cost	570,055
Total available-for-sale securities, Amortized cost	779,080	$ 549,627
Fair value
Due in one year or less	0
Due after one year through five years	76,786
Due after five years through ten years	72,198
Due after ten years	62,134
Total fair value	211,118
Mortgage-related securities-FNMA, FHLMC and GNMA - fair value	574,719
Available-for-sale securities	$ 785,837	$ 550,394