Selected Quarterly Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended																12 Months Ended
		Dec. 31, 2017		Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Interest Income (Expense), Net		$ 57,272	[1]	$ 56,627	[1]	$ 57,145	[1]	$ 53,642	[1]	$ 51,519	[1]	$ 49,871	[1]	$ 49,169	[1]	$ 49,879	[1]	$ 224,686		$ 200,438		$ 185,770
Noninterest Income		39,175	[1]	40,267	[1]	38,018	[1]	36,506	[1]	43,958	[1]	40,012	[1]	36,795	[1]	38,022	[1]	153,966		158,787		161,169
Revenue, Net	[1]	96,447		96,894		95,163		90,148		95,477		89,883		85,964		87,901
Provision/ (credit) for loan losses		(942)	[1]	(432)	[1]	(6,114)	[1]	(181)	[1]	(1,128)	[1]	(138)	[1]	(2,535)	[1]	(3,133)	[1]	(7,669)		(6,935)		(1,555)
Noninterest Expense		93,989	[1]	69,346	[1]	67,821	[1]	68,780	[1]	71,843	[1]	61,670	[1]	64,731	[1]	66,709	[1]	299,936		264,953		255,181
Income before income taxes		3,400	[1]	27,980	[1]	33,456	[1]	21,549	[1]	24,762	[1]	28,351	[1]	23,768	[1]	24,325	[1]	86,385		101,207		93,313
Income tax expense		21,391	[1]	8,289	[1]	9,963	[1]	6,553	[1]	7,247	[1]	8,652	[1]	7,626	[1]	7,438	[1]	46,196	[2]	30,963	[2]	30,392	[2]
Net income from discontinued operations		989	[1]	1,186	[1]	1,063	[1]	1,632	[1]	1,184	[1]	1,047	[1]	1,245	[1]	2,065	[1]	4,870	[3]	5,541	[3]	6,411	[3]
Net Income (Loss) Attributable to Noncontrolling Interest		1,278	[1]	1,074	[1]	1,150	[1]	966	[1]	1,147	[1]	1,110	[1]	989	[1]	911	[1]	4,468		4,157		4,407
Net income attributable to the Company		$ (18,280)	[1]	$ 19,803	[1]	$ 23,406	[1]	$ 15,662	[1]	$ 17,552	[1]	$ 19,636	[1]	$ 16,398	[1]	$ 18,041	[1]	$ 40,591		$ 71,628		$ 64,925
Earnings (Loss) Per Share, Basic		$ (0.24)	[1],[4]	$ 0.23	[1],[4]	$ 0.28	[1],[4]	$ 0.18	[1],[4]	$ 0.19	[1],[4]	$ 0.23	[1],[4]	$ 0.19	[1],[4]	$ 0.22	[1],[4]	$ 0.43		$ 0.83		$ 0.77
Earnings/ (Loss) Per Share, Diluted		$ (0.24)	[1],[4]	$ 0.22	[1],[4]	$ 0.27	[1],[4]	$ 0.17	[1],[4]	$ 0.19	[1],[4]	$ 0.22	[1],[4]	$ 0.18	[1],[4]	$ 0.21	[1],[4]	$ 0.42		$ 0.81		$ 0.74

[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 2017, 2016, and 2015 is not consistent due to the re-measurement of the deferred tax assets, impairment of goodwill not deductible for tax purposes, 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 2017, 2016, and 2015. See Part II. Item 8. “Financial Statements and Supplementary Data - Note 17: Income Taxes” for additional details.

[3] The Holding Company and Eliminations calculation of Net Income attributable to the Company includes net income from Discontinued Operations for the years ended December 31, 2017, 2016 and 2015 of $4.9 million, $5.5 million, and $6.4 million, respectively

[4] Includes the effect of adjustments to net income attributable to the Company to arrive at net income attributable to common shareholders.