Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2012

Commitments And Contingencies [Abstract]

Schedule of future minimum rental payments on operating leases

	Amount
2013	$	11,163
2014		10,541
2015		8,711
2016		7,986
2017		7,402
2018 through 2022		20,078
	$	65,881

Schedule of concentration of credit risk

	Year Ended December 31,
	2012		2011		2010
Marsh & McLennan Companies, Inc.		25%		23%		24%
Aon Corporation (including Benfield Group Ltd.)		19%		21%		20%
Willis Group Holdings		11%		11%		9%