Note Offsetting of financial assets and liabilities (Offsetting of financial assets) (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Derivative Asset Fair Value Net
Derivatives gross amount of recognized asset	$ 13,154	$ 16,959
Derivatives gross amount offset in the statement of financial position	0	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	13,154	16,959
Derivatives gross amount not offset financial instruments	286	114
Derivatives gross amount not offset securities collateral received	0	0
Derivatives gross amount not offset cash collateral received	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	12,868	16,845
Securities Purchased Under Agreements To Resell Amount Offset Against Collateral
Reverse repurchase agreement gross amount of recognized asset	86,328	96,338
Reverse repurchase agreement gross amount offset in the statement of financial position	0	0
Securities Purchased Under Agreements To Resell	86,328	96,338
Reverse repurchase agreement gross amount not offset financial instrument	0	0
Reverse repurchase agreement gross amount not offset securities collateral received	86,328	96,338
Reverse repurchase agreement gross amount not offset cash collateral received	0	0
Securities Purchased under Agreements to Resell, Amount Offset Against Collateral, Total	0	0
Offsetting Derivative Asset Securities Purchased Under Agreements To Resell Securities Borrowed [Abstract]
Total gross amount of recognized assets	99,482	113,297
Total gross amount offset in the statement of financial position	0	0
Derivative Asset Securities Purchased Under Agreements To Resell Securities Borrowed	99,482	113,297
Total gross amount not offset financial instruments	286	114
Total gross amount not offset securities collateral received	86,328	96,338
Total gross amounts not offset cash collateral received	0	0
Derivative Asset Securities Purchased Under Agreements To Resell Securities Borrowed Amount Offset Against Collateral	$ 12,868	$ 16,845