Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share ) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Income from continuing operations	$ 11,172	$ 17,179	$ 20,888	$ 43,097	$ 45,488	$ 40,093	$ 45,577	$ 47,973	$ 92,336	$ 179,130	$ 172,907
Loss from discontinued operations, net of tax					(306)	(190)	(1,976)	(591)		(3,063)	(10,894)
Net income	$ 11,172	$ 17,179	$ 20,888	$ 43,097	$ 45,182	$ 39,903	$ 43,601	$ 47,382	$ 92,336	$ 176,067	$ 162,013
Average shares used in basic computation	68,150	69,633	68,370	68,006	66,851	66,691	66,302	66,037	68,543	66,472	63,568
Dilutive effect of stock options and units									10,011	9,904	9,936
Average shares used in diluted computation	79,355	79,759	77,856	77,359	77,540	76,681	75,641	75,691	78,554	76,376	73,504
Income from continuing operations	$ 0.16	$ 0.25	$ 0.31	$ 0.62	$ 0.67	$ 0.60	$ 0.69	$ 0.73	$ 1.35	$ 2.69	$ 2.72
Loss from discontinued operations							(0.03)	(0.01)		(0.04)	(0.17)
Earnings per basic common share	0.16	0.25	0.31	0.62	0.67	0.60	0.66	0.72	1.35	2.65	2.55
Income from continuing operations	0.14	0.22	0.27	0.56	0.59	0.52	0.60	0.63	1.18	2.35	2.35
Loss from discontinued operations					(0.01)		(0.02)			(0.04)	(0.15)
Earnings per diluted common share	$ 0.14	$ 0.22	$ 0.27	$ 0.56	$ 0.58	$ 0.52	$ 0.58	$ 0.63	$ 1.18	$ 2.31	$ 2.20