Fair Value Measurements Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Level 1 [Member]
Mortgages Held-for-sale, Fair Value Disclosure	$ 0	$ 0
Available-for-sale Securities, Fair Value Disclosure	29,300	34,586
Other Assets, Fair Value Disclosure	13,746	13,130
Assets, Fair Value Disclosure	43,046	47,716
Liabilities, Fair Value Disclosure	13,746	13,130
Level 1 [Member] \| Equity Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	29,300	34,586
Level 1 [Member] \| U.S. Government Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	0	0
Level 1 [Member] \| U.S. Government-Sponsored Agency Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	0	0
Level 1 [Member] \| State and Municipal Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	0	0
Level 1 [Member] \| Corporate Debt Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	0	0
Level 1 [Member] \| Collateralized Mortgage Obligations [Member]
Available-for-sale Securities, Fair Value Disclosure	0	0
Level 1 [Member] \| Mortgage-Backed Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	0	0
Level 1 [Member] \| Auction Rate Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	0	0
Level 2 [Member]
Mortgages Held-for-sale, Fair Value Disclosure	71,406	47,009
Available-for-sale Securities, Fair Value Disclosure	2,546,459	2,321,748
Other Assets, Fair Value Disclosure	8,999	3,901
Assets, Fair Value Disclosure	2,626,864	2,372,658
Liabilities, Fair Value Disclosure	4,593	2,734
Level 2 [Member] \| Equity Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	0	0
Level 2 [Member] \| U.S. Government Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	327	334
Level 2 [Member] \| U.S. Government-Sponsored Agency Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	3,992	4,073
Level 2 [Member] \| State and Municipal Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	303,480	322,018
Level 2 [Member] \| Corporate Debt Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	121,257	114,017
Level 2 [Member] \| Collateralized Mortgage Obligations [Member]
Available-for-sale Securities, Fair Value Disclosure	981,657	1,001,209
Level 2 [Member] \| Mortgage-Backed Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	1,135,746	880,097
Level 2 [Member] \| Auction Rate Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	0	0
Level 3 [Member]
Mortgages Held-for-sale, Fair Value Disclosure	0	0
Available-for-sale Securities, Fair Value Disclosure	212,400	234,500
Other Assets, Fair Value Disclosure	0	0
Assets, Fair Value Disclosure	212,400	234,500
Liabilities, Fair Value Disclosure	0	0
Level 3 [Member] \| Equity Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	0	0
Level 3 [Member] \| U.S. Government Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	0	0
Level 3 [Member] \| U.S. Government-Sponsored Agency Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	0	0
Level 3 [Member] \| State and Municipal Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	0	0
Level 3 [Member] \| Corporate Debt Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	9,118	9,289
Level 3 [Member] \| Collateralized Mortgage Obligations [Member]
Available-for-sale Securities, Fair Value Disclosure	0	0
Level 3 [Member] \| Mortgage-Backed Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	0	0
Level 3 [Member] \| Auction Rate Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	203,282	225,211
Total [Member]
Mortgages Held-for-sale, Fair Value Disclosure	71,406	47,009
Available-for-sale Securities, Fair Value Disclosure	2,788,159	2,590,834
Other Assets, Fair Value Disclosure	22,745	17,031
Assets, Fair Value Disclosure	2,882,310	2,654,874
Liabilities, Fair Value Disclosure	18,339	15,864
Total [Member] \| Equity Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	29,300	34,586
Total [Member] \| U.S. Government Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	327	334
Total [Member] \| U.S. Government-Sponsored Agency Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	3,992	4,073
Total [Member] \| State and Municipal Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	303,480	322,018
Total [Member] \| Corporate Debt Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	130,375	123,306
Total [Member] \| Collateralized Mortgage Obligations [Member]
Available-for-sale Securities, Fair Value Disclosure	981,657	1,001,209
Total [Member] \| Mortgage-Backed Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	1,135,746	880,097
Total [Member] \| Auction Rate Securities [Member]
Available-for-sale Securities, Fair Value Disclosure	$ 203,282	$ 225,211

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

+ References+ Details