Consolidated Statements Of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net income	$ 31,804	$ 28,560
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Depreciation and amortization	3,831	3,581
Bad debt provision	1,675	1,550
Deferred income tax (benefits)	(1,466)	1,486
Stock-based compensation expense	1,733	1,531
Amortization of premium on marketable securities	185	174
Unrealized gains on deferred compensation fund investments	(482)	(888)
Changes in operating assets and liabilities:
Accounts and notes receivable	(6,879)	(16,695)
Inventories and supplies	69	(472)
Prepaid expenses and other assets	(2,199)	(4,191)
Deferred compensation funding	(243)	(1,803)
Accounts payable and other accrued expenses	(9,479)	(1,942)
Accrued payroll, accrued and withheld payroll taxes	(4,854)	(3,338)
Accrued insurance claims	6,354	740
Deferred compensation liability	952	3,031
Income taxes payable	12,512	3,503
Net cash provided by operating activities	33,513	14,827
Cash flows from investing activities:
Disposals of fixed assets	67	363
Additions to property and equipment	(2,289)	(2,738)
Purchases of marketable securities	(3,025)	(1,937)
Sales of marketable securities	2,813	2,115
Net cash used in investing activities	(2,434)	(2,197)
Cash flows from financing activities:
Dividends paid	(25,415)	(24,263)
Reissuance of treasury stock pursuant to Dividend Reinvestment Plan	54	28
Tax benefit from equity compensation plans	817	885
Proceeds from the exercise of stock options	4,085	3,834
Net cash used in financing activities	(20,459)	(19,516)
Net change in cash and cash equivalents	10,620	(6,886)
Cash and cash equivalents at beginning of the period	75,280	64,155
Cash and cash equivalents at end of the period	85,900	57,269
Supplementary Cash Flow Information:
Cash paid for interest	35	73
Cash paid for income taxes, net of refunds	7,643	10,737
Issuance of Common Stock in 2015 and 2014, respectively, pursuant to Employee Stock Purchase Plan	$ 1,701	$ 1,851