Employee Benefit Plans (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 years	Dec. 31, 2010	Dec. 31, 2009
Defined Benefit Plan Disclosure [Line Items]
Estimated transition obligation amortized from accumulated other comprehensive income into net periodic benefit cost over the next year	$ 0
Estimated actuarial loss amortized from accumulated other comprehensive income into net periodic benefit cost over the next year	7,062
Estimated prior service cost amortized from accumulated other comprehensive income into net periodic benefit cost over the next year	49
Weighted average discount rates used to determine net periodic benefit cost	5.60%	6.10%	6.25%
Rate of compensation increase to determine the net periodic benefit cost	4.00%	4.00%	4.00%
Expected long-term rate of return on plan assets	8.00%	8.00%	8.00%
Weighted average discount rates used to determine actuarial present value of the projected benefit obligation	4.60%	5.60%	6.10%
Plan assets consist of shares in investment trusts, equity securities	64.00%
Plan assets consist of shares in investment trusts, fixed maturities	33.00%
Plan assets consist of shares in investment trusts, cash	3.00%
Target asset allocation percentage of assets, in equity securities	70.00%
Target asset allocation percentage of assets, in bonds	30.00%
Defined contribution plans, employer contribution percentage, maximum	3.00%
Defined contribution plans, employer contribution percentage, for new hires, minimum	3.00%
Defined contribution plans, employer contribution percentage, for new hires, maximum	8.00%
Vested contribution after three years, percentage	100.00%
Defined contribution plans vesting period, years	3
Defined contribution plans, employer contribution percentage, for branch offices, minimum	1.60%
Defined contribution plans, employer contribution percentage, for branch offices, maximum	12.10%
Pre-Medicare Claims [Member]
Defined Benefit Plan Disclosure [Line Items]
Healthcare inflation rate	7.90%
Healthcare inflation rate decreased	4.50%
Post-Medicare Claims [Member]
Defined Benefit Plan Disclosure [Line Items]
Healthcare inflation rate	6.40%
Healthcare inflation rate decreased	4.50%
Post-Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated transition obligation amortized from accumulated other comprehensive income into net periodic benefit cost over the next year	0
Estimated actuarial loss amortized from accumulated other comprehensive income into net periodic benefit cost over the next year	328
Estimated prior service cost amortized from accumulated other comprehensive income into net periodic benefit cost over the next year	$ 0
Weighted average discount rates used to determine net periodic benefit cost	5.60%	6.10%	6.25%
Weighted average discount rates used to determine actuarial present value of the projected benefit obligation	4.60%	5.60%	6.10%