Bank segment - Credit risk profile - assigned grades (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Credit risk profile by internally assigned grade for loans
Commercial real estate	$ 618,113	$ 531,917
Commercial construction	80,230	96,438
Commercial	798,428	791,757
Pass
Credit risk profile by internally assigned grade for loans
Commercial real estate	563,734	493,105
Commercial construction	70,950	79,312
Commercial	745,624	743,334
Special mention
Credit risk profile by internally assigned grade for loans
Commercial real estate	9,460	5,209
Commercial construction	9,280	0
Commercial	10,316	16,095
Substandard
Credit risk profile by internally assigned grade for loans
Commercial real estate	44,919	33,603
Commercial construction	0	17,126
Commercial	40,662	31,665
Doubtful
Credit risk profile by internally assigned grade for loans
Commercial	$ 1,826	$ 663