Loans and leases (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Other [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at the beginning of period	$ 447,505	$ 531,546	$ 0
Additions	648,631	13,747	640,080
Interest income	(268,315)	(171,207)	(108,534)
Reclassifications from (to) nonaccretable balance, net	1,800	34,000
Other	(21,661)	39,419
Balance at end of period	807,960	447,505	531,546
Purchase Impaired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at the beginning of period	9,245	4,318	0
Additions	39,358	4,922	6,381
Interest income	(26,221)	(5,826)	(1,834)
Reclassifications from (to) nonaccretable balance, net	8,629	5,831	(229)
Other	(206)
Balance at end of period	$ 30,805	$ 9,245	$ 4,318