Business Combinations (Pro Forma Impact Of Business Combination and Acquisitions) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Business Acquisition [Line Items]
Revenues, Pro Forma	$ 513,186	[1]	$ 498,059	[1]	$ 492,594	[1]
Net income, Pro Forma	152,020	[1]	17,434	[1]	50,680	[1]
Net income (loss) attributable to common shareholders, Pro Forma	$ 108,809	[1]	$ (19,160)	[1]	$ 10,172	[1]
Earnings per share - basic, Pro Forma	$ 0.90	[1]	$ (0.16)	[1]	$ 0.08	[1]
Earnings per share - diluted, Pro Forma	$ 0.89	[1]	$ (0.16)	[1]	$ 0.08	[1]

[1] There are no non-recurring pro forma adjustments included within or excluded from the amounts in the preceding table.