Condensed Consolidating Statement Of Cash Flows (Details) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Jun. 30, 2014
Condensed Consolidating Financial Statements [Line Items]
Net cash provided (used) by operating activities		$ 37,930,000	$ 65,832,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment in property and equipment		(14,554,000)	(7,314,000)
Proceeds from sales of assets		6,283,000	12,216,000
Contributions to equity method investments		(2,446,000)	(6,946,000)
Distributions from equity method investments		270,000	0
Purchases of investments, employee benefit plans		(1,736,000)	(1,220,000)
Proceeds from sales of investments, employee benefit plans		1,087,000	641,000
Issuance of mezzanine and other notes receivable		(1,500,000)	(2,223,000)
Collections of mezzanine and other notes receivable		3,567,000	9,743,000
Other items, net		(261,000)	(296,000)
Net cash provided (used) in investing activities		(9,290,000)	4,601,000
CASH FLOWS FROM FINANCING ACTIVITIES:
Net borrowings pursuant to revolving credit facility		13,000,000	0
Proceeds from issuance of long term debt		0	26,000
Principal payments on long-term debt		(6,169,000)	(4,112,000)
Purchases of treasury stock		(6,244,000)	(4,544,000)
Dividends paid		(22,940,000)	(21,957,000)
Excess tax benefits from stock-based compensation		4,613,000	1,319,000
Proceeds from exercise of stock options	$ 100,000	5,696,000	1,547,000
Net cash provided (used) by financing activities		(12,044,000)	(27,721,000)
Net change in cash and cash equivalents		16,596,000	42,712,000
Effect of foreign exchange rate changes on cash and cash equivalents		(825,000)	1,035,000
Cash and cash equivalents at beginning of period		214,879,000	167,795,000
Cash and cash equivalents at end of period	230,650,000	230,650,000	211,542,000
Parent [Member]
Condensed Consolidating Financial Statements [Line Items]
Net cash provided (used) by operating activities		25,842,000	53,132,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment in property and equipment		(11,351,000)	(1,797,000)
Proceeds from sales of assets		29,000	27,000
Contributions to equity method investments		0	0
Distributions from equity method investments		0
Purchases of investments, employee benefit plans		0	0
Proceeds from sales of investments, employee benefit plans		0	0
Issuance of mezzanine and other notes receivable		(1,500,000)	(2,223,000)
Collections of mezzanine and other notes receivable		3,567,000	9,743,000
Advances to and investments in affiliates		0	(1,000,000)
Proceeds from Sale of Other Assets, Investing Activities		0
Other items, net		(261,000)	(296,000)
Net cash provided (used) in investing activities		(9,516,000)	4,454,000
CASH FLOWS FROM FINANCING ACTIVITIES:
Net borrowings pursuant to revolving credit facility		13,000,000
Proceeds from issuance of long term debt			0
Principal payments on long-term debt		(5,625,000)	(3,750,000)
Proceeds from contributions from affiliates		0	0
Purchases of treasury stock		(6,244,000)	(4,544,000)
Dividends paid		(22,940,000)	(21,957,000)
Excess tax benefits from stock-based compensation		110,000	295,000
Payments of Distributions to Affiliates		0
Proceeds from exercise of stock options		5,696,000	1,547,000
Net cash provided (used) by financing activities		(16,003,000)	(28,409,000)
Net change in cash and cash equivalents		323,000	29,177,000
Effect of foreign exchange rate changes on cash and cash equivalents		0	0
Cash and cash equivalents at beginning of period		25,290,000	9,785,000
Cash and cash equivalents at end of period	25,613,000	25,613,000	38,962,000
Guarantor Subsidiaries [Member]
Condensed Consolidating Financial Statements [Line Items]
Net cash provided (used) by operating activities		(5,396,000)	(1,383,000)
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment in property and equipment		(3,187,000)	(5,235,000)
Proceeds from sales of assets		4,661,000	12,189,000
Contributions to equity method investments		(1,659,000)	(1,283,000)
Distributions from equity method investments		0
Purchases of investments, employee benefit plans		(1,736,000)	(1,220,000)
Proceeds from sales of investments, employee benefit plans		1,087,000	641,000
Issuance of mezzanine and other notes receivable		0	0
Collections of mezzanine and other notes receivable		0	0
Advances to and investments in affiliates		(35,000)	(4,842,000)
Proceeds from Sale of Other Assets, Investing Activities		2,122,000
Other items, net		0	0
Net cash provided (used) in investing activities		1,253,000	250,000
CASH FLOWS FROM FINANCING ACTIVITIES:
Net borrowings pursuant to revolving credit facility		0
Proceeds from issuance of long term debt			0
Principal payments on long-term debt		(356,000)	(349,000)
Proceeds from contributions from affiliates		0	0
Purchases of treasury stock		0	0
Dividends paid		0	0
Excess tax benefits from stock-based compensation		4,503,000	1,024,000
Payments of Distributions to Affiliates		0
Proceeds from exercise of stock options		0	0
Net cash provided (used) by financing activities		4,147,000	675,000
Net change in cash and cash equivalents		4,000	(458,000)
Effect of foreign exchange rate changes on cash and cash equivalents		0	0
Cash and cash equivalents at beginning of period		25,000	569,000
Cash and cash equivalents at end of period	29,000	29,000	111,000
Non-Guarantor Subsidiaries [Member]
Condensed Consolidating Financial Statements [Line Items]
Net cash provided (used) by operating activities		18,141,000	14,740,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment in property and equipment		(16,000)	(282,000)
Proceeds from sales of assets		1,593,000	0
Contributions to equity method investments		(787,000)	(5,663,000)
Distributions from equity method investments		270,000
Purchases of investments, employee benefit plans		0	0
Proceeds from sales of investments, employee benefit plans		0	0
Issuance of mezzanine and other notes receivable		0	0
Collections of mezzanine and other notes receivable		0	0
Advances to and investments in affiliates		0	0
Proceeds from Sale of Other Assets, Investing Activities		0
Other items, net		0	0
Net cash provided (used) in investing activities		1,060,000	(5,945,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net borrowings pursuant to revolving credit facility		0
Proceeds from issuance of long term debt			26,000
Principal payments on long-term debt		(188,000)	(13,000)
Proceeds from contributions from affiliates		35,000	5,842,000
Purchases of treasury stock		0	0
Dividends paid		(657,000)	(657,000)
Excess tax benefits from stock-based compensation		0	0
Payments of Distributions to Affiliates		(2,122,000)
Proceeds from exercise of stock options		0	0
Net cash provided (used) by financing activities		(2,932,000)	5,198,000
Net change in cash and cash equivalents		16,269,000	13,993,000
Effect of foreign exchange rate changes on cash and cash equivalents		(825,000)	1,035,000
Cash and cash equivalents at beginning of period		189,564,000	157,441,000
Cash and cash equivalents at end of period	205,008,000	205,008,000	172,469,000
Eliminations [Member]
Condensed Consolidating Financial Statements [Line Items]
Net cash provided (used) by operating activities		(657,000)	(657,000)
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment in property and equipment		0	0
Proceeds from sales of assets		0	0
Contributions to equity method investments		0	0
Distributions from equity method investments		0
Purchases of investments, employee benefit plans		0	0
Proceeds from sales of investments, employee benefit plans		0	0
Issuance of mezzanine and other notes receivable		0	0
Collections of mezzanine and other notes receivable		0	0
Advances to and investments in affiliates		35,000	5,842,000
Proceeds from Sale of Other Assets, Investing Activities		(2,122,000)
Other items, net		0	0
Net cash provided (used) in investing activities		(2,087,000)	5,842,000
CASH FLOWS FROM FINANCING ACTIVITIES:
Net borrowings pursuant to revolving credit facility		0
Proceeds from issuance of long term debt			0
Principal payments on long-term debt		0	0
Proceeds from contributions from affiliates		(35,000)	(5,842,000)
Purchases of treasury stock		0	0
Dividends paid		657,000	657,000
Excess tax benefits from stock-based compensation		0	0
Payments of Distributions to Affiliates		2,122,000
Proceeds from exercise of stock options		0	0
Net cash provided (used) by financing activities		2,744,000	(5,185,000)
Net change in cash and cash equivalents		0	0
Effect of foreign exchange rate changes on cash and cash equivalents		0	0
Cash and cash equivalents at beginning of period		0	0
Cash and cash equivalents at end of period	0	0	0
Consolidated [Member]
Condensed Consolidating Financial Statements [Line Items]
Net cash provided (used) by operating activities		37,930,000	65,832,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Investment in property and equipment		(14,554,000)	(7,314,000)
Proceeds from sales of assets		6,283,000	12,216,000
Contributions to equity method investments		(2,446,000)	(6,946,000)
Distributions from equity method investments		270,000
Purchases of investments, employee benefit plans		(1,736,000)	(1,220,000)
Proceeds from sales of investments, employee benefit plans		1,087,000	641,000
Issuance of mezzanine and other notes receivable		(1,500,000)	(2,223,000)
Collections of mezzanine and other notes receivable		3,567,000	9,743,000
Advances to and investments in affiliates		0	0
Proceeds from Sale of Other Assets, Investing Activities		0
Other items, net		(261,000)	(296,000)
Net cash provided (used) in investing activities		(9,290,000)	4,601,000
CASH FLOWS FROM FINANCING ACTIVITIES:
Net borrowings pursuant to revolving credit facility		13,000,000
Proceeds from issuance of long term debt			26,000
Principal payments on long-term debt		(6,169,000)	(4,112,000)
Proceeds from contributions from affiliates		0	0
Purchases of treasury stock		(6,244,000)	(4,544,000)
Dividends paid		(22,940,000)	(21,957,000)
Excess tax benefits from stock-based compensation		4,613,000	1,319,000
Payments of Distributions to Affiliates		0
Proceeds from exercise of stock options		5,696,000	1,547,000
Net cash provided (used) by financing activities		(12,044,000)	(27,721,000)
Net change in cash and cash equivalents		16,596,000	42,712,000
Effect of foreign exchange rate changes on cash and cash equivalents		(825,000)	1,035,000
Cash and cash equivalents at beginning of period		214,879,000	167,795,000
Cash and cash equivalents at end of period	$ 230,650,000	$ 230,650,000	$ 211,542,000