Reorganization (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Restructuring Reserve [Roll Forward]
Restructuring reserve	$ 37,828	$ 0
Charges	31,403	85,629
Non-cash adjustment		(24,194)
Cash payments	(50,386)	(23,607)
Restructuring reserve	18,845	37,828
Amount expected to be incurred, including charges to date	120,387
Severance and retention
Restructuring Reserve [Roll Forward]
Restructuring reserve	36,565	0
Charges	26,359	51,706
Non-cash adjustment		0
Cash payments	(44,602)	(15,141)
Restructuring reserve	18,322	36,565
Amount expected to be incurred, including charges to date	81,420
Long-lived asset impairments and contract and lease terminations
Restructuring Reserve [Roll Forward]
Restructuring reserve	770	0
Charges	5,077	22,337
Non-cash adjustment		(21,247)
Cash payments	(5,324)	(320)
Restructuring reserve	523	770
Amount expected to be incurred, including charges to date	27,414
Other transaction costs
Restructuring Reserve [Roll Forward]
Restructuring reserve	493	0
Charges	(33)	11,586
Non-cash adjustment		(2,947)
Cash payments	(460)	(8,146)
Restructuring reserve	0	493
Amount expected to be incurred, including charges to date	11,553
Premium deficiency charges
Restructuring Reserve [Roll Forward]
Restructuring reserve	78,047
Restructuring reserve	40,388	$ 78,047
Amount expected to be incurred, including charges to date	303,014
Premium deficiency charges	$ 182,627