Segment information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Information about the Company's segments
Total Revenue	$ 997,112	$ 883,224
Net income (loss)	206,463	206,273
Business Banking [Member]
Information about the Company's segments
Total Revenue	111,976	99,777
Inter-segment revenues	1,092	962
Net income (loss)	35,333	26,300
Commercial Banking [Member]
Information about the Company's segments
Total Revenue	237,462	213,612
Inter-segment revenues	1,540	1,166
Net income (loss)	103,096	88,331
Commercial Real Estate [Member]
Information about the Company's segments
Total Revenue	153,544	125,306
Inter-segment revenues	433	356
Net income (loss)	68,631	49,010
Discretionary Portfolio [Member]
Information about the Company's segments
Total Revenue	(1,160)	42,483
Inter-segment revenues	(14,781)	(7,787)
Net income (loss)	(8,241)	16,127
Residential Mortgage Banking [Member]
Information about the Company's segments
Total Revenue	93,042	57,848
Inter-segment revenues	34,441	10,307
Net income (loss)	23,517	4,785
Retail Banking [Member]
Information about the Company's segments
Total Revenue	306,848	295,048
Inter-segment revenues	2,892	2,987
Net income (loss)	48,657	52,726
All Other [Member]
Information about the Company's segments
Total Revenue	95,400	49,150
Inter-segment revenues	(25,617)	(7,991)
Net income (loss)	$ (64,530)	$ (31,006)