14. Leases (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Finance Lease, Right-Of-Use Asset, before Accumulated Amortization	$ 11,500		$ 11,500		$ 11,400
Finance Lease, Right-Of-Use Asset, Accumulated Amortization	4,400		4,400		4,200
Finance Lease, Right-Of-Use Asset, after Accumulated Amortization	7,100		7,100		$ 7,200
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	21,000		21,000
Finance Lease, Liability, Payments, Remainder of Fiscal Year	$ 1,300		$ 1,300
Operating Lease, Weighted Average Remaining Lease Term	9 years		9 years		9 years
Finance Lease, Weighted Average Remaining Lease Term	18 years		18 years		18 years
Operating Lease, Weighted Average Discount Rate, Percent	4.10%		4.10%		4.20%
Finance Lease, Liability, Current	$ 500		$ 500		$ 500
Finance Lease, Liability, Noncurrent	11,100		11,100		11,200
Finance Lease, Liability	$ 11,600		$ 11,600		$ 11,700
Finance Lease, Weighted Average Discount Rate, Percent	6.60%		6.60%		6.50%
Lessee, Operating Lease, Liability, Payments, Due Year Two	$ 38,700		$ 38,700
Finance Lease, Liability, Payments, Due Year Two	1,200		1,200
Lessee, Operating Lease, Liability, Payments, Due Year Three	31,700		31,700
Finance Lease, Liability, Payments, Due Year Three	1,200		1,200
Lessee, Operating Lease, Liability, Payments, Due Year Four	26,800		26,800
Finance Lease, Liability, Payments, Due Year Four	1,100		1,100
Lessee, Operating Lease, Liability, Payments, Due Year Five	23,600		23,600
Finance Lease, Liability, Payments, Due Year Five	1,100		1,100
Lessee, Operating Lease, Liability, Payments, Due after Year Five	107,300		107,300
Finance Lease, Liability, Payments, Due after Year Five	14,600		14,600
Lessee, Operating Lease, Liability, Payments, Due	249,100		249,100
Finance Lease, Liability, Payment, Due	20,500		20,500
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(42,100)		(42,100)
Finance Lease, Liability, Undiscounted Excess Amount	(8,900)		(8,900)
Operating lease right-of-use assets	197,588		197,588		$ 201,868
Operating Lease, Payments	10,900	$ 11,300	22,200	$ 22,900
Operating Lease, Cost	12,400	12,100	25,000	24,500
Finance Lease, Right-of-Use Asset, Amortization	100	200	300	400
Finance Lease, Interest Expense	200	300	400	500
Finance Lease Cost	300	500	700	900
Sublease Income	700	700	1,500	1,500
Finance Lease, Interest Payment on Liability	200	300	400	500
Finance Lease, Principal Payments	100	100	300	400
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	2,200	4,500	7,600	5,800
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	100	$ 0	100	$ 0
Current operating lease liabilities	33,941		33,941		35,365
Operating lease liabilities	173,103		173,103		176,018
Operating Lease, Liability	$ 207,000		$ 207,000		$ 211,400
Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee Operating And Finance Leases Remaining Lease Term			1 year
Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee Operating And Finance Leases Remaining Lease Term			19 years