14. Leases (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	$ 13,400	$ 14,200	$ 38,400	$ 38,700
Finance Lease, Right-of-Use Asset, Amortization	100	100	400	500
Finance Lease, Interest Expense	200	200	600	700
Finance Lease Cost	300	300	1,000	1,200
Sublease Income	700	700	2,200	2,200
Operating Lease, Payments	10,800	11,600	33,000	34,500
Finance Lease, Interest Payment on Liability	100	200	400	700
Finance Lease, Principal Payments	200	100	600	500
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	800	14,400	8,400	20,200
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	100	$ 100	200	$ 100
Operating lease right-of-use assets	196,652		196,652		$ 201,868
Current operating lease liabilities	34,387		34,387		35,365
Operating lease liabilities	172,144		172,144		176,018
Operating Lease, Liability	206,500		206,500		211,400
Finance Lease, Right-Of-Use Asset, before Accumulated Amortization	11,700		11,700		11,400
Finance Lease, Right-Of-Use Asset, Accumulated Amortization	4,600		4,600		4,200
Finance Lease, Right-Of-Use Asset, after Accumulated Amortization	7,100		7,100		7,200
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
Operating Lease, Weighted Average Remaining Lease Term	9 years		9 years		9 years
Finance Lease, Weighted Average Remaining Lease Term	17 years		17 years		18 years
Operating Lease, Weighted Average Discount Rate, Percent	4.00%		4.00%		4.20%
Finance Lease, Weighted Average Discount Rate, Percent	6.50%		6.50%		6.50%
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	$ 10,800		$ 10,800
Finance Lease, Liability, Payments, Remainder of Fiscal Year	1,200		1,200
Lessee, Operating Lease, Liability, to be Paid, Year One	41,100		41,100
Finance Lease, Liability, to be Paid, Year One	1,200		1,200
Lessee, Operating Lease, Liability, Payments, Due Year Two	33,800		33,800
Finance Lease, Liability, Payments, Due Year Two	1,100		1,100
Lessee, Operating Lease, Liability, Payments, Due Year Three	28,700		28,700
Finance Lease, Liability, Payments, Due Year Three	1,100		1,100
Lessee, Operating Lease, Liability, Payments, Due Year Four	24,800		24,800
Finance Lease, Liability, Payments, Due Year Four	1,100		1,100
Lessee, Operating Lease, Liability, Payments, Due after Year Five	111,500		111,500
Finance Lease, Liability, Payments, Due after Year Five	13,300		13,300
Lessee, Operating Lease, Liability, Payments, Due	250,700		250,700
Finance Lease, Liability, Payment, Due	19,000		19,000
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(44,200)		(44,200)
Finance Lease, Liability, Undiscounted Excess Amount	$ (7,400)		$ (7,400)
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