Retirement Plans (Tables)

6 Months Ended

Jun. 30, 2013

Compensation And Retirement Disclosure [Abstract]

Components of Net Periodic Benefits Cost

The following table shows the components of net periodic benefits cost included in expense for the plans.

	Three Months Ended June 30,
	2013			2012			2013		2012
							Other Post-
	Pension benefits						retirement Benefits
Service cost	$	4,007		$	3,247		$	55	$	48
Interest cost		4,362			4,302			330		361
Expected return on plan assets		(7,701	)		(6,350	)		—		—
Amortization of prior service cost		—			—			—		(14	)
Amortization of net loss		1,463			1,646			823		177
Amortization of transition obligation		—			—			—		1
Net periodic benefit cost	$	2,131		$	2,845		$	1,208	$	573
	Six Months Ended June 30,
	2013			2012			2013		2012
	Pension benefits						Other Post- retirement Benefits
Service cost	$	7,936		$	6,494		$	110	$	96
Interest cost		8,306			8,603			660		722
Expected return on plan assets		(13,964	)		(12,699	)		—		—
Amortization of prior service cost		—			—			—		(28	)
Amortization of net loss		3,208			3,291			861		354
Amortization of transition obligation		—			—			—		3
Net periodic benefit cost	$	5,486		$	5,689		$	1,631	$	1,147