Segment information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Information about the Company's segments
Total Revenue	$ 1,039,633	$ 1,087,858	$ 2,036,745	$ 1,971,082
Net income (loss)	233,380	322,358	439,843	528,631
Business Banking [Member]
Information about the Company's segments
Total Revenue	109,318	104,012	221,294	203,789
Inter-segment revenues	1,099	971	2,191	1,933
Net income (loss)	37,085	26,584	72,418	52,884
Commercial Banking [Member]
Information about the Company's segments
Total Revenue	248,754	228,564	486,216	442,176
Inter-segment revenues	1,731	1,190	3,271	2,356
Net income (loss)	99,623	95,111	202,719	183,442
Commercial Real Estate [Member]
Information about the Company's segments
Total Revenue	168,083	134,066	321,627	259,372
Inter-segment revenues	396	448	829	804
Net income (loss)	80,498	65,058	149,129	114,068
Discretionary Portfolio [Member]
Information about the Company's segments
Total Revenue	(11,807)	112,383	(12,967)	154,866
Inter-segment revenues	(20,616)	(4,419)	(35,397)	(12,206)
Net income (loss)	(14,757)	58,362	(22,998)	74,489
Residential Mortgage Banking [Member]
Information about the Company's segments
Total Revenue	109,995	58,305	203,037	116,153
Inter-segment revenues	37,455	8,699	71,896	19,006
Net income (loss)	25,994	5,966	49,511	10,751
Retail Banking [Member]
Information about the Company's segments
Total Revenue	313,994	311,484	620,842	606,532
Inter-segment revenues	3,198	2,967	6,090	5,954
Net income (loss)	58,191	54,645	106,848	107,371
All Other [Member]
Information about the Company's segments
Total Revenue	101,296	139,044	196,696	188,194
Inter-segment revenues	(23,263)	(9,856)	(48,880)	(17,847)
Net income (loss)	$ (53,254)	$ 16,632	$ (117,784)	$ (14,374)