Acquisition Activity - Pro Forma Information (Details) - Sabadell United - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Business Acquisition [Line Items]
Net interest income	$ 232,828	$ 688,846
Non-interest income	54,511	164,360
Net income	$ 30,825	$ 163,968