Equity Change in OCI Recognized in Statement of Operations, Line Item (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification adjustment for net realized gain included in net income																	$ 28		$ 557		$ 490
Gain on sale of investments, net																	49		871		798
Income tax expense/(benefit)	7,303	[1]	8,557	[1]	10,551	[1]	5,897	[1]	6,115	[1]	5,124	[1]	5,240	[1]	3,851	[1]	32,308	[2]	20,330	[2]	14,280	[2]
Net income attributable to the Company	17,668	[1]	18,336	[1]	21,328	[1]	13,203	[1]	13,092	[1]	16,513	[1]	14,161	[1]	9,505	[1]	70,535		53,271		39,137
Interest Expense, Deposits																	13,395		17,640		24,479
Net income from discontinued operations	1,968	[1]	1,321	[1]	2,781	[1]	1,722	[1]	1,819	[1]	1,672	[1]	2,590	[1]	1,554	[1]	7,792		7,635		6,184
Interest Expense, Junior Subordinated Debentures																	4,408		6,258		7,434
Salaries and employee benefits																	140,761		143,852		142,872
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax																	(1,204)		(1,038)		(523)
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Reclassification Out of Accumulated Comprehensive Income, Pre-tax [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of investments, net																	49		871		798
Net income from discontinued operations																	0		(35)		0
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Reclassification Out of Accumulated Comprehensive Income, Tax effect [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense/(benefit)																	21		314		308
Net income from discontinued operations																	0		(12)		0
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income attributable to the Company																	28		557		490
Net income from discontinued operations																	0		(23)		0
Hedges related to junior subordinated debt [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification Out of Accumulated Comprehensive Income, Pre-tax [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest Expense, Junior Subordinated Debentures																	1,894		1,757		1,872
Hedges related to junior subordinated debt [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification Out of Accumulated Comprehensive Income, Tax effect [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense/(benefit)																	799		742		777
Hedges related to junior subordinated debt [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income attributable to the Company																	(1,095)		(1,015)		(1,095)
Hedges related to deposits [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification Out of Accumulated Comprehensive Income, Pre-tax [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest Expense, Deposits																	189		0		0
Hedges related to deposits [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification Out of Accumulated Comprehensive Income, Tax effect [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense/(benefit)																	80		0		0
Hedges related to deposits [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income attributable to the Company																	(109)		0		0
Special Termination Benefits [Member] | Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification Out of Accumulated Comprehensive Income, Pre-tax [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits																	0		0		659
Special Termination Benefits [Member] | Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification Out of Accumulated Comprehensive Income, Tax effect [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense/(benefit)																	0		0		232
Special Termination Benefits [Member] | Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income attributable to the Company																	0		0		427
Pension and Other Postretirement Plans Costs [Member] | Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification Out of Accumulated Comprehensive Income, Pre-tax [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits																	0		0		415
Pension and Other Postretirement Plans Costs [Member] | Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification Out of Accumulated Comprehensive Income, Tax effect [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense/(benefit)																	0		0		145
Pension and Other Postretirement Plans Costs [Member] | Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income attributable to the Company																	$ 0		$ 0		$ 270

[1] Due to rounding, the sum of the four quarters may not add to the year to date total.

[2] The Company’s effective tax rate for 2013, 2012, and 2011 are not consistent due to earnings from tax-exempt investments, non-deductible compensation, state and local taxes, income tax credits and income attributable to noncontrolling interests having a different impact on the effective tax rate due primarily to the different levels of income before taxes in years 2013, 2012, and 2011. See Part II. Item 8. “Financial Statements and Supplementary Data - Note 17: Income Taxes” for additional details.