Employee Benefit Plans (Schedule of Components of Net Periodic Benefit Cost) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Compensation and Retirement Disclosure [Abstract]
Service cost	$ 1,061	$ 1,133	$ 3,422	$ 3,197
Interest cost	110	106	338	294
Expected return on plan assets	(125)	(108)	(385)	(307)
Employee contributions	(283)	(274)	(868)	(781)
Amortization of prior service costs	73	64	224	182
Total net periodic benefit cost	$ 836	$ 921	$ 2,731	$ 2,585