Fair Value Measurements Not Measured at Fair Value on a Recurring Basis (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Fair Value, Measurements, Nonrecurring [Member]		Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member]		Sep. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member]		Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member]		Sep. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member]		Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member]		Sep. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]		Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]		Sep. 30, 2014 Reported Value Measurement, Fair Value Disclosure [Member]	Mar. 31, 2014 Reported Value Measurement, Fair Value Disclosure [Member]	Dec. 31, 2013 Reported Value Measurement, Fair Value Disclosure [Member]	Sep. 30, 2014 Portion at Fair Value Measurement, Fair Value Disclosure [Member]	Mar. 31, 2014 Portion at Fair Value Measurement, Fair Value Disclosure [Member]	Dec. 31, 2013 Portion at Fair Value Measurement, Fair Value Disclosure [Member]	Sep. 30, 2014 Portion at Fair Value Measurement, Fair Value Disclosure [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2013 Portion at Fair Value Measurement, Fair Value Disclosure [Member] Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2014 Portion at Fair Value Measurement, Fair Value Disclosure [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2013 Portion at Fair Value Measurement, Fair Value Disclosure [Member] Fair Value, Inputs, Level 2 [Member]	Sep. 30, 2014 Portion at Fair Value Measurement, Fair Value Disclosure [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2013 Portion at Fair Value Measurement, Fair Value Disclosure [Member] Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure																			$ 308,912		$ 191,881	$ 308,912		$ 191,881	$ 308,912	$ 191,881	$ 0	$ 0	$ 0	$ 0
Held-to-maturity Securities, Fair Value	133,141	110,917																		132,467	112,014		133,141	110,917	0	0	133,141	110,917	0	0
Loans Receivable, Fair Value Disclosure			3,825	[1]	9,464	[2]	0	[1]	0	[2]	0	[1]	0	[2]	3,825	[1]	9,464	[2]	5,138,208		5,036,088	5,071,670		4,985,555	0	0	0	0	5,071,670	4,985,555
Loans Held-for-sale, Fair Value Disclosure																			4,943		6,123	5,374		6,130	0	0	5,374	6,130	0	0
Other Assets, Fair Value Disclosure																			112,492		117,840	112,492		117,840	0	0	112,492	117,840	0	0
Deposits, Fair Value Disclosure																			5,334,881		5,110,370	5,337,618		5,113,224	0	0	5,337,618	5,113,224	0	0
Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure																			73,422		102,353	73,415		102,343	0	0	73,415	102,343	0	0
Federal Home Loan Bank Borrowings, Fair Value Disclosure																			371,367		367,254	378,697		377,384	0	0	378,697	377,384	0	0
Subordinated Debt Obligations, Fair Value Disclosure																			106,363		106,363	96,363		96,363	0	0	0	0	96,363	96,363
Other Liabilities, Fair Value Disclosure																			$ 7,515		$ 9,789	$ 7,515		$ 9,789	$ 0	$ 0	$ 7,515	$ 9,789	$ 0	$ 0

[1] Collateral-dependent impaired loans held at September 30, 2014 that had write-downs in fair value or whose specific reserve changed during the first nine months of 2014.

[2] Collateral-dependent impaired loans held at September 30, 2013 that had write-downs in fair value or whose specific reserve changed during the first nine months of 2013.