Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2011

Benefit Plans (Tables) [Abstract]

Components of Net Periodic Benefit Cost

	Three Months Ended
	June 30,
	Pension Benefits						Other Benefits
	2011			2010			2011			2010
Components of net periodic benefit cost
Service cost	$	2,713		$	2,499		$	—		$	—
Interest cost		7,872			7,681			232			248
Expected return on plan assets		(10,184	)		(9,603	)		—			—
Amortization of prior service cost		64			49			(129	)		(129	)
Recognized net actuarial loss		2,394			1,344			97			71
Net periodic pension benefit cost	$	2,859		$	1,970		$	200		$	190

	Six Months Ended
	June 30,
	Pension Benefits						Other Benefits
	2011			2010			2011			2010
Components of net periodic benefit cost
Service cost	$	5,426		$	4,998		$	—		$	—
Interest cost		15,744			15,362			465			496
Expected return on plan assets		(20,367	)		(19,206	)		—			—
Amortization of prior service cost		129			97			(258	)		(258	)
Recognized net actuarial loss		4,800			2,717			194			142
Net periodic pension benefit cost	$	5,732		$	3,968		$	401		$	380