Regulatory Matters (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Parent Company [Member]
Regulatory Capital [Abstract]
Total Capital Actual Amount	$ 2,167,954		$ 2,263,065
Total Capital for Capital Adequacy Purposes Amount	1,291,923		1,165,466
Total Capital Actual Ratio	13.42%	[1]	15.53%	[1]
Total Capital for Adequacy Purposes Ratio	8.00%	[1]	8.00%	[1]
Tier 1 Capital Actual Amount	1,938,806		2,051,787
Tier 1 Capital for Adequacy Purposes Amount	645,962		582,733
Tier 1 Capital Actual Ratio	12.01%	[1]	14.08%	[1]
Tier 1 Capital for Adequacy Purposes Ratio	4.00%	[1]	4.00%	[1]
Tier 1 Leverage Capital Actual Amount	1,938,806		2,051,787
Tier 1 Leverage Capital for Adequacy Purposes Amount	863,674		836,537
Tier 1 Leverage Capital Actual Ratio	8.98%	[1]	9.81%	[1]
Tier 1 Leverage Capital for Adequacy Purposes Ratio	4.00%	[1]	4.00%	[1]
Subsidiaries [Member]
Regulatory Capital [Abstract]
Total Capital Actual Amount	2,448,280		2,369,363
Total Capital for Capital Adequacy Purposes Amount	1,277,222		1,148,924
Total Capital to be Well Capitalized Amount	1,596,527	[2]	1,436,155	[2]
Total Capital Actual Ratio	15.34%	[1]	16.50%	[1]
Total Capital for Adequacy Purposes Ratio	8.00%	[1]	8.00%	[1]
Total Capital to be Well Capitalized Ratio	10.00%	[1]	10.00%	[1]
Tier 1 Capital Actual Amount	2,247,307		2,186,776
Tier 1 Capital for Adequacy Purposes Amount	638,611		574,462
Tier 1 Capital To Be Well Capitalized Amount	957,916	[2]	861,693	[2]
Tier 1 Capital Actual Ratio	14.08%	[1]	15.23%	[1]
Tier 1 Capital for Adequacy Purposes Ratio	4.00%	[1]	4.00%	[1]
Tier 1 Capital To Be Well Capitalized Ratio	6.00%	[1]	6.00%	[1]
Tier 1 Leverage Capital Actual Amount	2,247,307		2,186,776
Tier 1 Leverage Capital for Adequacy Purposes Amount	853,553		828,505
Tier 1 Leverage Capital To Be Well Capitalized Amount	$ 1,066,941	[2]	$ 1,035,632	[2]
Tier 1 Leverage Capital Actual Ratio	10.53%	[1]	10.56%	[1]
Tier 1 Leverage Capital for Adequacy Purposes Ratio	4.00%	[1]	4.00%	[1]
Tier 1 Leverage Capital To Be Well Capitalized Ratio	5.00%	[1]	5.00%	[1]

[1]  Total Capital ratio is defined as Tier 1 capital plus Tier 2 capital divided by total risk-weighted assets. The Tier 1 Capital ratio is defined as Tier 1 capital divided by total risk-weighted assets. The leverage ratio is defined as Tier 1 capital divided by the most recent quarter’s average total assets.

[2]  Prompt corrective action provisions are not applicable at the bank holding company level.