Stock-Based Compensation Stock and Performance Options Rollforward (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Employee Stock Option
Shares
Beginning balance (in shares) | shares	6,192,315
Granted (in shares) | shares	21,924
Exercised (in shares) | shares	(240,887)
Forfeited (in shares) | shares	(36,662)
Expired (in shares) | shares	(493,770)
End balance (in shares) | shares	5,442,920
Exercisable at December 31, 2018 (in shares) | shares	4,529,180
Weighted Average Exercise Price
Beginning balance (in usd per share) | $ / shares	$ 21.51
Granted (in usd per share) | $ / shares	15.55
Exercised (in usd per share) | $ / shares	6.87
Forfeited (in usd per share) | $ / shares	6.87
Expired (in usd per share) | $ / shares	65.40
Ending balance (in usd per share) | $ / shares	18.74
Exercisable at December 31, 2018 (in usd per share) | $ / shares	$ 21.09
Weighted average remaining contractual term (in years), outstanding	4 years 9 months 14 days
Weighted average remaining contractual term (in years), exercisable	4 years 3 months 21 days
Aggregate intrinsic value, outstanding | $	$ 12,485
Aggregate intrinsic value, exercisable | $	$ 8,431
Performance Options
Shares
End balance (in shares) | shares	927,268
Exercisable at December 31, 2018 (in shares) | shares	927,268
Weighted Average Exercise Price
Ending balance (in usd per share) | $ / shares	$ 39.00
Exercisable at December 31, 2018 (in usd per share) | $ / shares	$ 39.00
Weighted average remaining contractual term (in years), outstanding	1 year 5 months 1 day
Weighted average remaining contractual term (in years), exercisable	1 year 5 months 1 day