Postretirement Benefit Plans (Details) (Expected Benefit Payments) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Defined Benefit Postretirement Health And Life Coverage [Member]
Defined Benefit Plan Disclosure [Line Items]
1/1/2013 to 12/31/2013	$ 37
1/1/2014 to 12/31/2014	47
1/1/2015 to 12/31/2015	64
1/1/2016 to 12/31/2016	73
1/1/2017 to 12/31/2017	69
1/1/2018 to 12/31/2022	370
Director's Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
1/1/2013 to 12/31/2013	87
1/1/2014 to 12/31/2014	89
1/1/2015 to 12/31/2015	92
1/1/2016 to 12/31/2016	94
1/1/2017 to 12/31/2017	96
1/1/2018 to 12/31/2022	$ 491