Leases - Balance Sheet Disclosures and Components of Lease Expense (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Leases [Abstract]
Right of Use Asset	$ 38,303,000		$ 38,303,000		$ 41,254,000
Operating lease liability	$ 45,897,000		$ 45,897,000		$ 49,367,000
Weighted-average remaining lease term-operating leases (Year)	7 years 2 months 12 days		7 years 2 months 12 days		8 years
Weighted average discount rate-operating leases	3.80%		3.80%		3.80%
Operating lease cost	$ 1,897,000	$ 1,893,000	$ 3,782,000	$ 3,785,000
Short-term lease cost	34,000	34,000	68,000	68,000
Variable lease cost	287,000	244,000	552,000	423,000
Total lease cost	2,218,000	2,171,000	4,402,000	4,276,000
Operating cash flows from operating leases	2,200,000	2,025,000	4,182,000	4,050,000
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 27,000	$ 21,000	$ 50,000	$ 42,000