Acquisition (Details) (USD $)	3 Months Ended			12 Months Ended		3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2012 Kenny [Member]	Dec. 31, 2012 Kenny [Member] employee office	Dec. 31, 2012 Notes Payable to Banks [Member]	Mar. 31, 2012 Construction [Member] Kenny [Member]
Business Acquisition [Line Items]
Total purchase price				$ 141,114,000
Amortization expense	2,200,000	1,100,000	200,000			1,700,000
Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Cash And Equivalents				53,185,000
Proceeds from Lines of Credit					70,000,000
Business Acquisitions, Pro Forma Information, Expected Adjustments				$ 8,500,000
Entity Number of Employees				475
Number Of Offices				12