Investment securities Other Narratives - HTM securities (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Sep. 30, 2014 USD ($) Number_of_securities	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Held-to-maturity Securities [Abstract]
Available for sale securities transferred to held to maturity, number of securities | Number_of_securities	86
Available for sale securities transferred to held to maturity, carrying value	$ 50,882	$ 0	$ 50,882	$ 0
Available for sale securities transferred to held to maturity securities, fair value	51,371
Available for sale securities transferred to held to maturity, unrealized gains	$ 489