Segment information (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Information about the Company's segments
Total Revenue	$ 985,101	$ 859,767	$ 2,956,183	$ 2,514,591
Net income (loss)	183,108	192,015	711,739	531,719
Business Banking [Member]
Information about the Company's segments
Total Revenue	110,627	103,475	314,416	307,881
Inter-segment revenues	957	290	2,890	290
Net income (loss)	31,237	24,295	84,121	76,191
Commercial Banking [Member]
Information about the Company's segments
Total Revenue	230,023	199,139	672,199	586,120
Inter-segment revenues	1,318	282	3,674	282
Net income (loss)	93,783	71,567	277,225	230,047
Commercial Real Estate [Member]
Information about the Company's segments
Total Revenue	152,878	118,666	412,250	338,566
Inter-segment revenues	410	104	1,214	161
Net income (loss)	65,566	53,727	179,634	141,147
Discretionary Portfolio [Member]
Information about the Company's segments
Total Revenue	16,437	12,493	171,303	5,840
Inter-segment revenues	(3,968)	(2,733)	(16,174)	(7,980)
Net income (loss)	2,077	(2,759)	76,566	(22,994)
Residential Mortgage Banking [Member]
Information about the Company's segments
Total Revenue	67,757	73,744	183,910	202,627
Inter-segment revenues	25,012	9,419	44,018	26,492
Net income (loss)	10,805	9,408	21,556	9,536
Retail Banking [Member]
Information about the Company's segments
Total Revenue	314,113	302,656	920,645	925,769
Inter-segment revenues	2,583	2,632	8,537	8,009
Net income (loss)	43,947	55,572	151,318	181,689
All Other [Member]
Information about the Company's segments
Total Revenue	93,266	49,594	281,460	147,788
Inter-segment revenues	(26,312)	(9,994)	(44,159)	(27,254)
Net income (loss)	$ (64,307)	$ (19,795)	$ (78,681)	$ (83,897)