Retirement Plans (Tables)

6 Months Ended

Jun. 30, 2011

Retirement Plans [Abstract]

Net period benefit cost for the pension and postretirement plans

	Three Months Ended						Six Months Ended						Year Ended
	June 30,						June 30,						December 31,
	2011			2010			2011			2010			2010
	($ in Thousands)
Components of Net Periodic Benefit Cost
Pension Plan:
Service cost	$	2,613		$	2,475		$	5,225		$	4,950		$	9,622
Interest cost		1,589			1,590			3,180			3,180			6,377
Expected return on plan assets		(3,220	)		(3,019	)		(6,440	)		(6,038	)		(12,152	)
Amortization of prior service cost		18			18			35			35			72
Amortization of actuarial loss		451			405			903			810			1,601
Total net periodic benefit cost	$	1,451		$	1,469		$	2,903		$	2,937		$	5,520
Postretirement Plan:
Interest cost	$	50		$	58		$	100		$	115		$	227
Amortization of prior service cost		99			99			198			198			395
Amortization of actuarial gain		—			—			—			—			(3	)
Total net periodic benefit cost	$	149		$	157		$	298		$	313		$	619