Selected Quarterly Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Net interest income	$ 59,997	$ 59,641	$ 57,545	$ 57,383	$ 57,272	$ 56,627	$ 57,145	$ 53,642	$ 234,566	$ 224,686	$ 200,438
Fees and other income	45,845	32,314	32,095	39,743	39,175	40,267	38,018	36,506	149,997	153,966	158,787
Total revenues	105,842	91,955	89,640	97,126	96,447	96,894	95,163	90,148	384,563	378,652	359,225
Provision/ (credit) for loan losses	93	(949)	453	(1,795)	(942)	(432)	(6,114)	(181)	(2,198)	(7,669)	(6,935)
Operating expense	63,557	68,557	64,384	70,857	93,989	69,346	67,821	68,780	267,355	299,936	264,953
Income before income taxes	42,192	24,347	24,803	28,064	3,400	27,980	33,456	21,549	119,406	86,385	101,207
Income tax expense	8,651	5,461	17,399	6,026	21,391	8,289	9,963	6,553	37,537	46,196	30,963
Net income from discontinued operations	306	0	(2)	1,698	989	1,186	1,063	1,632	2,002	4,870	5,541
Less: Net income attributable to noncontrolling interests	545	924	968	1,050	1,278	1,074	1,150	966	3,487	4,468	4,157
Net income attributable to the Company	$ 33,302	$ 17,962	$ 6,434	$ 22,686	$ (18,280)	$ 19,803	$ 23,406	$ 15,662	$ 80,384	$ 40,591	$ 71,628
Basic earnings (in dollars per share)	$ 0.43	$ 0.20	$ 0.03	$ 0.27	$ (0.24)	$ 0.23	$ 0.28	$ 0.18	$ 0.94	$ 0.43	$ 0.83
Diluted earnings (in dollars per share)	$ 0.42	$ 0.20	$ 0.03	$ 0.27	$ (0.24)	$ 0.22	$ 0.27	$ 0.17	$ 0.92	$ 0.42	$ 0.81