PENSION AND POSTRETIREMENT LIABILITIES:

3 Months Ended

Mar. 31, 2013

PENSION AND POSTRETIREMENT LIABILITIES:

PENSION AND POSTRETIREMENT LIABILITIES:

11.  PENSION AND POSTRETIREMENT LIABILITIES:

The following table represents the net periodic benefit cost of defined benefit pension plans:

	Three months ended
	March 31,
($ in millions)	2013			2012
Service cost	$	3.3		$	2.4
Interest cost	6.9			7.9
Expected return on assets	(3.6		)	(3.9		)
Amortization of actuarial losses	4.2			1.8
Amortization of prior service cost	0.2			0.2
Total pension cost	$	11.0		$	8.4

Contributions to defined benefit pension plans, including benefit payments paid directly to plan participants, are expected to approximate $25.8 million during 2013, of which $6.8 million was contributed in the three months ended March 31, 2013.

The Company also sponsors and participates in various defined contribution and multi-employer plans. The expense for the defined contribution plans was $3.3 million and $3.8 million for the three months ended March 31, 2013 and 2012, respectively, and $1.8 million and $1.3 million for the multi-employer plans for the three months ended March 31, 2013 and 2012, respectively.