Pension Plans and Other Postretirement Benefits Changes in Fair Value of Plans Level 3 Assets (Details) - Total Pension Benefits - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning balance	[1]	$ 607,694
Fair value of plan assets, Ending Balance	[1]	690,787		$ 607,694
Unobservable Inputs (Level 3)
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning balance		80,740	[1]	123,599
Transfers in due to acquisition		103,237
Purchases		5,641		50,506
Sales		(103,035)		(96,397)
Total losses relating to assets sold during the period		(610)	[2]	(158)	[3]
Total unrealized gains (losses) included in earnings relating to assets still held at the reporting date		(2,846)	[2]	3,190	[3]
Fair value of plan assets, Ending Balance	[1]	$ 83,127		$ 80,740

[1] See Note 15 “Pension Plans and Other Postretirement Benefits” for further information about fair value measurements of our pension and postretirement plan assets, including the reconciliations of the plans’ Level 3 assets.

[2] These losses are recognized in the consolidated balance sheets and are included as changes in plan assets in the tables above.

[3] These (losses) gains are recognized in the consolidated balance sheets and are included as changes in plan assets in the tables above.