Earnings Per Share (Reconciliation of EPS) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Basic EPS: [Abstract]
Net income from continuing operations	$ 41,350	$ 53,162	$ 29,341	$ 17,974	$ 25,335	$ 32,653	$ 27,122	$ 22,305	$ 141,827	$ 107,415	$ 37,963
Loss on disposal of discontinued operations									0	(997)	0
Net income	41,350us-gaap_NetIncomeLoss	53,162us-gaap_NetIncomeLoss	29,341us-gaap_NetIncomeLoss	17,974us-gaap_NetIncomeLoss	25,335us-gaap_NetIncomeLoss	32,653us-gaap_NetIncomeLoss	27,122us-gaap_NetIncomeLoss	21,308us-gaap_NetIncomeLoss	141,827us-gaap_NetIncomeLoss	106,418us-gaap_NetIncomeLoss	37,963us-gaap_NetIncomeLoss
Net income, basic shares									56,310	55,638	54,880
Basic net income from continuing operations									$ 2.52	$ 1.93	$ 0.69
Basic net loss from discontinued operations									$ 0.00	$ (0.02)	$ 0.00
Basic net income	$ 0.73us-gaap_EarningsPerShareBasic	$ 0.94us-gaap_EarningsPerShareBasic	$ 0.52us-gaap_EarningsPerShareBasic	$ 0.32us-gaap_EarningsPerShareBasic	$ 0.45us-gaap_EarningsPerShareBasic	$ 0.59us-gaap_EarningsPerShareBasic	$ 0.49us-gaap_EarningsPerShareBasic	$ 0.38us-gaap_EarningsPerShareBasic	$ 2.52us-gaap_EarningsPerShareBasic	$ 1.91us-gaap_EarningsPerShareBasic	$ 0.69us-gaap_EarningsPerShareBasic
Effect of dilutive securities: [Abstract]
Stock compensation plans, shares									1,041	1,172	1,053
Earnings Per Share, Diluted [Abstract]
Net income from continuing operations	41,350	53,162	29,341	17,974	25,335	32,653	27,122	22,305	141,827	107,415	37,963
Loss on disposal of discontinued operations									0	(997)	0
Net income	$ 41,350us-gaap_NetIncomeLoss	$ 53,162us-gaap_NetIncomeLoss	$ 29,341us-gaap_NetIncomeLoss	$ 17,974us-gaap_NetIncomeLoss	$ 25,335us-gaap_NetIncomeLoss	$ 32,653us-gaap_NetIncomeLoss	$ 27,122us-gaap_NetIncomeLoss	$ 21,308us-gaap_NetIncomeLoss	$ 141,827us-gaap_NetIncomeLoss	$ 106,418us-gaap_NetIncomeLoss	$ 37,963us-gaap_NetIncomeLoss
Shares net income, Diluted									57,351	56,810	55,933
Diluted net income from continuing operations									$ 2.47	$ 1.89	$ 0.68
Diluted net loss from discontinued operations									$ 0.00	$ (0.02)	$ 0.00
Diluted net income	$ 0.72us-gaap_EarningsPerShareDiluted	$ 0.93us-gaap_EarningsPerShareDiluted	$ 0.51us-gaap_EarningsPerShareDiluted	$ 0.31us-gaap_EarningsPerShareDiluted	$ 0.44us-gaap_EarningsPerShareDiluted	$ 0.57us-gaap_EarningsPerShareDiluted	$ 0.48us-gaap_EarningsPerShareDiluted	$ 0.38us-gaap_EarningsPerShareDiluted	$ 2.47us-gaap_EarningsPerShareDiluted	$ 1.87us-gaap_EarningsPerShareDiluted	$ 0.68us-gaap_EarningsPerShareDiluted

Amount of increase (decrease) to net income used for calculating diluted earnings per share (EPS), resulting from the assumed exercise of stock options or restrictive stock units (RSUs).

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