Consolidated Statement of Other Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 216,612	$ 184,644	$ 145,401
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax	(8,956)	5,591	(17)
Defined Benefit Plan, Amortization of Transition Obligations (Assets)	(87)	(87)	(87)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	159	159	159
Defined Benefit Plan, Amortization of Gains (Losses)	0	326	378
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax	2,210	(1,521)	(104)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	209,938	189,112	145,730
Net Income (Loss) Attributable to Noncontrolling Interest	541	(40)	484
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 209,397	$ 189,152	$ 145,246