Allowance for Loan Losses - Summary of Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 56,390	$ 52,775
Charge-offs	(1,450)	(2,942)
Recoveries	1,634	800
Net (Charge-offs)/ Recoveries	184	(2,142)
Provision for loan losses	2,472	5,183
Balance at End of Period	59,046	55,816
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	27,235	19,976
Charge-offs	0	(390)
Recoveries	49	78
Net (Charge-offs)/ Recoveries	49	(312)
Provision for loan losses	3,679	906
Balance at End of Period	30,963	20,570
Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	8,966	10,810
Charge-offs	(829)	(715)
Recoveries	117	187
Net (Charge-offs)/ Recoveries	(712)	(528)
Provision for loan losses	2,218	2,962
Balance at End of Period	10,472	13,244
Commercial construction
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	13,167	13,999
Charge-offs	0	(644)
Recoveries	1,129	256
Net (Charge-offs)/ Recoveries	1,129	(388)
Provision for loan losses	(3,575)	491
Balance at End of Period	10,721	14,102
Consumer real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	5,479	6,095
Charge-offs	(161)	(759)
Recoveries	238	103
Net (Charge-offs)/ Recoveries	77	(656)
Provision for loan losses	(138)	517
Balance at End of Period	5,418	5,956
Other consumer
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	1,543	1,895
Charge-offs	(460)	(434)
Recoveries	101	176
Net (Charge-offs)/ Recoveries	(359)	(258)
Provision for loan losses	288	307
Balance at End of Period	$ 1,472	$ 1,944