Note Fair value measurement (Changes in level 3 assets and liabilities measured at fair value on a recurring basis) (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Assets, Fair Value Disclosure [Abstract]
Beginning Balance	$ 172,149	$ 170,420
Gains (Losses) included in earnings	(3,832)	(4,317)
Gains (losses) included in OCI	2	1
Additions	1,875	2,573
Settlements	(30)	(83)
Ending Balance	170,164	168,594
Fair Value Assets Measured On Recurring Basis Change In Unrealized Gain Loss	(744)	5
Liabilities, Fair Value Disclosure [Abstract]
Beginning Balance		(164,858)
Liabilitiy - Gains (Losses) included in earnings		(6,112)
Gains (losses) included in OCI		0
Additions		0
Settlements		0
Ending Balance		(170,970)
Fair Value Liabilities Measured On Recurring Basis Change In Unrealized Gain Loss		(6,112)
Contingent consideration
Liabilities, Fair Value Disclosure [Abstract]
Beginning Balance		(164,858)
Liabilitiy - Gains (Losses) included in earnings		(6,112)
Gains (losses) included in OCI		0
Additions		0
Settlements		0
Ending Balance		(170,970)
Fair Value Liabilities Measured On Recurring Basis Change In Unrealized Gain Loss		(6,112)
Debt securities available-for-sale \| Mortgage Backed Securities
Assets, Fair Value Disclosure [Abstract]
Beginning Balance	1,233	1,288
Gains (Losses) included in earnings	0	0
Gains (losses) included in OCI	2	1
Additions	0	0
Settlements	0	(26)
Ending Balance	1,235	1,263
Fair Value Assets Measured On Recurring Basis Change In Unrealized Gain Loss	0	0
Trading account debt securities \| Mortgage Backed Securities
Assets, Fair Value Disclosure [Abstract]
Beginning Balance	43	43
Gains (Losses) included in earnings	0	0
Gains (losses) included in OCI	0	0
Additions	0	0
Settlements	0	0
Ending Balance	43	43
Fair Value Assets Measured On Recurring Basis Change In Unrealized Gain Loss	0	0
Trading account debt securities \| CMO
Assets, Fair Value Disclosure [Abstract]
Beginning Balance	611	529
Gains (Losses) included in earnings	0	0
Gains (losses) included in OCI	0	0
Additions	14	16
Settlements	(30)	(57)
Ending Balance	595	488
Fair Value Assets Measured On Recurring Basis Change In Unrealized Gain Loss	0	0
Trading account debt securities \| Other
Assets, Fair Value Disclosure [Abstract]
Beginning Balance	485	529
Gains (Losses) included in earnings	(7)	(10)
Gains (losses) included in OCI	0	0
Additions	0	0
Settlements	0	0
Ending Balance	478	519
Fair Value Assets Measured On Recurring Basis Change In Unrealized Gain Loss	3	5
Mortgage Servicing Rights
Assets, Fair Value Disclosure [Abstract]
Beginning Balance	169,777	168,031
Gains (Losses) included in earnings	(3,825)	(4,307)
Gains (losses) included in OCI	0	0
Additions	1,861	2,557
Settlements	0	0
Ending Balance	167,813	166,281
Fair Value Assets Measured On Recurring Basis Change In Unrealized Gain Loss	$ (747)	$ 0

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