Employee Benefit Plans (Details 6) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Key executives
Other employee benefit plans
Participant balances, reflected in other liabilities	$ 12,430	$ 13,330
Participant deferrals average interest rate (as a percent)	7.17%	6.72%
Reference rate	Moody's Average Annual Corporate Bond Index rate
Interest rate margin for actively employed participants (as a percent)	0.45%
Key executives | Minimum
Other employee benefit plans
Fixed rates for retired participants (as a percent)	6.37%
Key executives | Maximum
Other employee benefit plans
Fixed rates for retired participants (as a percent)	7.91%
Select group of management and highly compensated individuals
Other employee benefit plans
Participant balances, reflected in other liabilities	$ 12,239	$ 11,258