Earnings Per Share (Details) (USD $) In Thousands, except Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Basic EPS:
Income from continuing operations	$ 17,007	$ 9,403	$ 63,938	$ 36,156
Income from continuing operations, Shares	42,470,000	37,880,000	42,365,000	37,792,000
Less: Income from continuing operations allocated to unvested shares	(326)	(179)	(1,195)	(693)
Income from continuing operations allocated to common shares	16,681	9,224	62,743	35,463
Income from continuing operations allocated to common shares, Shares	42,470,000	37,880,000	42,365,000	37,792,000
Income from continuing operations allocated to common shares, per share amount	$ 0.39	$ 0.24	$ 1.48	$ 0.94
Dilutive Securities:
Plus: Income from continuing operations allocated to unvested shares	326	179	1,195	693
Less: Income from continuing operations re-allocated to unvested shares	(324)	(178)	(1,188)	(689)
Stock Options, Shares	208,000	178,000	254,000	203,000
Diluted EPS:
Income from continuing operations allocated to common shares, and assumed share conversions	$ 16,683	$ 9,225	$ 62,750	$ 35,467
Income from continuing operations allocated to common shares, and assumed share conversions, Shares	42,678,000	38,058,000	42,619,000	37,995,000
Income from continuing operations allocated to common shares, and assumed share conversions, per share amount	$ 0.39	$ 0.24	$ 1.47	$ 0.93
Earnings Per Share (Textual) [Abstract]
Options to purchase, shares	1,377,681	1,400,000	1,377,681	1,400,000	1,361,779
Options to purchase, exercise price	$ 32.44	$ 29.00	$ 32.44	$ 29.00
Stock options not included in the computation of diluted EPS	800,000	700,000	700,000	800,000