Note Goodwill and other intangible assets (Components of other intangible assets subject to amortization) (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 100,290	$ 101,204
Finite Lived Intangible Assets Accumulated Amortization	55,421	49,209
Finite-Lived Intangible Assets, Net	44,869	51,995
Core deposits
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Core Deposits, Gross	63,539	63,539
Finite Lived Intangible Assets Accumulated Amortization	41,800	38,464
Finite-Lived Intangible Assets, Net	21,739	25,075
Other customer relationship
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Customer Relationships, Gross	36,751	37,665
Finite Lived Intangible Assets Accumulated Amortization	13,621	10,745
Finite-Lived Intangible Assets, Net	$ 23,130	$ 26,920