Postretirement Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2016

Compensation and Retirement Disclosure [Abstract]

Summary of Post-Retirement Benefit Costs by Component

The following tables present a summary of post-retirement benefit costs by component.

Components of Post-Retirement Benefit Costs

	Three Months Ended June 30,
	Pension Benefits						Other Benefits
	2016			2015			2016		2015
Service cost	$	3,894		$	3,991		$	—	$	—
Interest cost	5,432			5,004			212		204
Expected return on assets	(5,782		)	(5,323		)	—		—
Amortization:
Prior service cost	120			82			—		—
Actuarial (gain) loss	2,423			3,534			8		37
Direct recognition of expense	—			—			20		151
Net periodic benefit cost	$	6,087		$	7,288		$	240	$	392
	Six Months Ended June 30,
	Pension Benefits						Other Benefits
	2016			2015			2016		2015
Service cost	$	7,788		$	7,981		$	—	$	—
Interest cost	10,864			10,006			424		407
Expected return on assets	(11,564		)	(10,646		)	—		—
Amortization:
Prior service cost	240			163			—		—
Actuarial (gain)/loss	4,847			7,068			16		60
Direct recognition of expense	—			—			54		327
Net periodic benefit cost	$	12,175		$	14,572		$	494	$	794

Schedule of Assets at Fair Value for Defined-Benefit Pension Plans

The following table presents assets at fair value for the defined-benefit pension plans at June 30, 2016 and the prior-year end.

Pension Assets by Component

	June 30, 2016			December 31, 2015
	Amount		%	Amount		%
Corporate debt	$	156,603	48	$	146,381	47
Other fixed maturities	281		—	270		—
Equity securities	124,419		38	123,428		40
Short-term investments	22,540		7	15,593		5
Guaranteed annuity contract	17,313		5	17,082		6
Other	5,593		2	4,842		2
Total	$	326,749	100	$	307,596	100