Leadership Changes and Restructuring Activities - Rollforward of Estimated Fair Value Liability Established for Total Severance and Other Related Costs (Details) - USD ($) $ in Thousands		6 Months Ended
	Apr. 09, 2016	Jun. 30, 2016	Jun. 30, 2015
Restructuring Cost and Reserve [Line Items]
Balance, January 1, 2015		$ 2,021
Severance and other related expense		1,043
Accretion		35
Cash payments		(1,302)
Non-cash adjustment		(1,311)	$ (668)
Balance, September 30, 2015		$ 1,466
Restricted Stock Units (RSUs)
Restructuring Cost and Reserve [Line Items]
Accelerated vesting of restricted stock units	12,109	43,688
Separation And Transition Agreement
Restructuring Cost and Reserve [Line Items]
Non-cash adjustment		$ (331)