Retirement Plans (Tables)

9 Months Ended

Sep. 30, 2012

Retirement Plans [Abstract]

Net period benefit cost for the pension and postretirement plans

		Three Months Ended				Nine Months Ended			Year Ended
		September 30,				September 30,			December 31,
		2012		2011		2012		2011	2011
Components of Net Periodic Benefit Cost		($ in Thousands)
Pension Plan:
Service cost	$	2,613	$	2,613	$	7,838	$	7,838	$	9,898
Interest cost		1,613		1,589		4,838		4,769		6,414
Expected return on plan assets		(3,558)		(3,220)		(10,673)		(9,660)		(12,896)
Amortization of prior service cost		17		18		52		53		72
Amortization of actuarial loss		640		451		1,920		1,354		2,024
Total net periodic benefit cost	$	1,325	$	1,451	$	3,975	$	4,354	$	5,512
Postretirement Plan:
Interest cost	$	47	$	50	$	142	$	150	$	198
Amortization of prior service cost		43		98		128		296		395
Total net periodic benefit cost	$	90	$	148	$	270	$	446	$	593