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Fair value of financial and nonfinancial obligations.

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Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

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Fair Value Measurement (Schedule Of Fair Value Assets And Liabilities Measured On Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	$ 10,452us-gaap_TradingSecurities	$ 9,999us-gaap_TradingSecurities
Available for sale, at fair value	2,535,121us-gaap_AvailableForSaleSecurities	2,298,555us-gaap_AvailableForSaleSecurities
Loans held for sale, at fair value	406,487	286,802
Residential mortgage servicing rights, at fair value	116,365us-gaap_ServicingAssetAtFairValueAmount	117,259us-gaap_ServicingAssetAtFairValueAmount	49,220us-gaap_ServicingAssetAtFairValueAmount	47,765us-gaap_ServicingAssetAtFairValueAmount
Total assets measured at fair value	3,113,201us-gaap_AssetsFairValueDisclosure	2,741,825us-gaap_AssetsFairValueDisclosure
Junior subordinated debentures, at fair value	250,652	249,294
Total liabilities measured at fair value	294,996us-gaap_LiabilitiesFairValueDisclosure	280,079us-gaap_LiabilitiesFairValueDisclosure
Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	37,487	26,327
Derivatives, liabilities	40,101	28,158
Interest Rate Forward Sales Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	264	16
Derivatives, liabilities	4,243	2,627
Interest Rate Lock Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	7,025	2,867
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Residential mortgage servicing rights, at fair value	0	0
Total assets measured at fair value	5,868	5,283
Junior subordinated debentures, at fair value	0	0
Total liabilities measured at fair value	0	0
Level 1 [Member] \| Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	0	0
Derivatives, liabilities	0	0
Level 1 [Member] \| Interest Rate Forward Sales Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	0	0
Derivatives, liabilities	0	0
Level 1 [Member] \| Interest Rate Lock Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	0	0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale, at fair value	406,487	286,802
Residential mortgage servicing rights, at fair value	0	0
Total assets measured at fair value	2,983,943	2,616,416
Junior subordinated debentures, at fair value	0	0
Total liabilities measured at fair value	44,344	30,785
Level 2 [Member] \| Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	37,487	26,327
Derivatives, liabilities	40,101	28,158
Level 2 [Member] \| Interest Rate Forward Sales Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	264	16
Derivatives, liabilities	4,243	2,627
Level 2 [Member] \| Interest Rate Lock Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	0	0
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Residential mortgage servicing rights, at fair value	116,365	117,259
Total assets measured at fair value	123,390	120,126
Junior subordinated debentures, at fair value	250,652	249,294
Total liabilities measured at fair value	250,652	249,294
Level 3 [Member] \| Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	0	0
Derivatives, liabilities	0	0
Level 3 [Member] \| Interest Rate Forward Sales Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	0	0
Derivatives, liabilities	0	0
Level 3 [Member] \| Interest Rate Lock Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	7,025	2,867
Obligations Of States And Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	92	124
Available for sale, at fair value	337,602	338,404
Obligations Of States And Political Subdivisions [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	0	0
Available for sale, at fair value	0	0
Obligations Of States And Political Subdivisions [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	92	124
Available for sale, at fair value	337,602	338,404
Obligations Of States And Political Subdivisions [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	0	0
Available for sale, at fair value	0	0
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	5,868	5,283
Equity Securities [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	5,868	5,283
Equity Securities [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	0	0
Equity Securities [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	0	0
Other Investments Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	4,492	4,592
Other Investments Securities [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	0	0
Other Investments Securities [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	4,492	4,592
Other Investments Securities [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	0	0
U.S. Treasury And Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	229	229
U.S. Treasury And Agencies [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	0	0
U.S. Treasury And Agencies [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	229	229
U.S. Treasury And Agencies [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	0	0
Residential Mortgage-Backed Securities And Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	2,195,201	1,957,852
Residential Mortgage-Backed Securities And Collateralized Mortgage Obligations [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	0	0
Residential Mortgage-Backed Securities And Collateralized Mortgage Obligations [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	2,195,201	1,957,852
Residential Mortgage-Backed Securities And Collateralized Mortgage Obligations [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	0	0
Investments In Mutual Funds And Other Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	2,089	2,070
Investments In Mutual Funds And Other Equity Securities [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	0	0
Investments In Mutual Funds And Other Equity Securities [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	2,089	2,070
Investments In Mutual Funds And Other Equity Securities [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	$ 0	$ 0