Quarterly Financial Information (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 593,771	$ 601,371	$ 607,849	$ 574,001	$ 590,636	$ 534,683	$ 568,989	$ 555,377	$ 2,376,993	$ 2,249,685	$ 2,019,814
Interest expense	12,485	9,796	10,098	13,019	12,560	11,228	8,842	8,631	45,399	41,261	46,368
Net revenues	581,286	591,575	597,751	560,982	578,076	523,455	560,147	546,746
Total non-interest expenses	570,204	569,227	559,680	490,916	508,698	457,689	482,624	468,618	2,190,027	1,917,630	1,788,217
Income from continuing operations before income tax expense	11,082	22,348	38,071	70,066	69,378	65,766	77,523	78,128	141,567	290,794	185,229
Provision for income taxes	(90)	5,169	17,183	26,969	23,890	25,673	31,946	30,155	49,231	111,664	12,322
Income from continuing operations	11,172	17,179	20,888	43,097	45,488	40,093	45,577	47,973	92,336	179,130	172,907
Loss from discontinued operations, net of tax					(306)	(190)	(1,976)	(591)		(3,063)	(10,894)
Net income	$ 11,172	$ 17,179	$ 20,888	$ 43,097	$ 45,182	$ 39,903	$ 43,601	$ 47,382	$ 92,336	$ 176,067	$ 162,013
Earnings per basic common share
Income from continuing operations	$ 0.16	$ 0.25	$ 0.31	$ 0.62	$ 0.67	$ 0.60	$ 0.69	$ 0.73	$ 1.35	$ 2.69	$ 2.72
Loss from discontinued operations							(0.03)	(0.01)		(0.04)	(0.17)
Earnings per basic common share	0.16	0.25	0.31	0.62	0.67	0.60	0.66	0.72	1.35	2.65	2.55
Earnings per diluted common share
Income from continuing operations	0.14	0.22	0.27	0.56	0.59	0.52	0.60	0.63	1.18	2.35	2.35
Income from discontinued operations					(0.01)		(0.02)			(0.04)	(0.15)
Earnings per diluted common share	$ 0.14	$ 0.22	$ 0.27	$ 0.56	$ 0.58	$ 0.52	$ 0.58	$ 0.63	$ 1.18	$ 2.31	$ 2.20
Weighted-average number of common shares outstanding:
Basic	68,150	69,633	68,370	68,006	66,851	66,691	66,302	66,037	68,543	66,472	63,568
Diluted	79,355	79,759	77,856	77,359	77,540	76,681	75,641	75,691	78,554	76,376	73,504