Operating Leases (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Other information related to leases [Abstract]
Operating lease cost		$ 1,930	$ 1,928	$ 3,821	$ 3,840
Variable lease cost		509	468	975	1,054
Total Lease costs		$ 2,439	2,396	4,796	4,894
Cash paid for amounts included in the measurement of lease liabilities [Abstract]
Operating cash flows from operating leases				3,906
Right-of-use assets obtained in exchange for lease obligations:				$ 54,038
Weighted average remaining lease term		9 years 7 months 6 days		9 years 7 months 6 days
Weighted average discount rate		3.30%		3.30%
Future minimum lease payments under non-cancellable leases [Abstract]
2019	[1]	$ 3,933		$ 3,933
2020		7,820		7,820
2021		7,818		7,818
2022		7,300		7,300
2023		6,978		6,978
Thereafter		32,600		32,600
Total lease payments		66,449		66,449
Less: Interest		10,212		10,212
Present value of lease liabilities		$ 56,237		$ 56,237		$ 0
Minimum annual lease payments under terms of leases [Abstract]
2018	[2]		3,881		3,881
2019			7,799		7,799
2020			7,622		7,622
2021			7,555		7,555
2022			7,048		7,048
Thereafter			39,395		39,395
Total lease payments			$ 73,300		$ 73,300
Minimum [Member]
Leases, operating [Abstract]
Operating lease expiration term		5 months		5 months
Maximum [Member]
Leases, operating [Abstract]
Operating lease expiration term		25 years 3 months 18 days		25 years 3 months 18 days

[1] Excluding the six months ended June 30, 2019.

[2] Excluding six months ended June 30, 2018.