Pension Plan and Employee Benefits Pension Plan and Employee Benefits, 401 (K) Plans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
401(k) Plan [Abstract]
401 (k) Plan expense	$ 4,375	$ 3,917	$ 3,709
Other Subsidiaries [Member]
401(k) Plan [Abstract]
401 (k) Plan expense	$ 1,000	$ 900	$ 800