Statement of Financial Position, Classified (Statement) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Assets, Current [Abstract]
Cash and Cash Equivalents, at Carrying Value	$ 184,055,000	$ 316,473,000
Marketable Securities, Current	0	19,999,000
Accounts Receivable, after Allowance for Credit Loss, Current	128,419,000	88,123,000
Prepaid Expense	26,600,000	18,956,000
Other Assets, Current	25,496,000	23,279,000
Income Taxes Receivable	5,205,000	5,856,000
Assets, Current	369,775,000	472,686,000
Assets, Noncurrent [Abstract]
Property, Plant and Equipment, Net	22,373,000	23,492,000
Operating Lease, Right-of-Use Asset	85,318,000	92,671,000
Assets for Plan Benefits, Defined Benefit Plan	13,853,000	14,425,000
Long-term Investments	33,545,000	31,369,000
Other Assets, Noncurrent	27,617,000	24,439,000
Goodwill	91,452,000	91,643,000
Other Intangible Assets, Net	961,000	1,129,000
Deferred Income Tax Assets, Net	35,712,000	35,958,000
Assets, Noncurrent	310,831,000	315,126,000
Assets	680,606,000	787,812,000
Liabilities, Current [Abstract]
Accounts Payable, Current	10,149,000	8,799,000
Employee-related Liabilities, Current	112,830,000	217,908,000
Deferred Revenue, Current	38,847,000	38,050,000
Operating Lease, Liability, Current	27,947,000	28,984,000
Other Liabilities, Current	20,114,000	23,311,000
Accrued Income Taxes, Current	7,383,000	1,186,000
Liabilities, Current	217,270,000	318,238,000
Liabilities, Noncurrent [Abstract]
Accrued Salaries and Benefits	44,301,000	56,925,000
Liability, Defined Benefit Plan, Noncurrent	54,826,000	53,496,000
Operating Lease, Liability, Noncurrent	81,536,000	86,816,000
Other Liabilities, Noncurrent	4,103,000	4,735,000
Liabilities, Noncurrent	184,766,000	201,972,000
Liabilities	402,036,000	520,210,000
Stockholders' Equity Attributable to Parent [Abstract]
Preferred Stock, Value, Issued	0	0
Common Stock, Value, Issued	196,000	196,000
Treasury Stock, Value	(3,090,000)	(8,041,000)
Additional Paid in Capital, Common Stock	225,998,000	231,048,000
Retained Earnings (Accumulated Deficit)	52,742,000	40,982,000
Accumulated Other Comprehensive Income (Loss), Net of Tax	2,724,000	3,417,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	278,570,000	267,602,000
Liabilities and Equity	$ 680,606,000	$ 787,812,000