Stock-Based Compensation (Stock Option Activity) (Details) - Stock Options - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2017	Jun. 30, 2017
Shares
Options, outstanding, beginning of period (in shares)	701,134	701,134
Options, granted (in shares)		537,030
Options, exercised (in shares)		(64,916)
Options, expired (in shares)		(46,088)
Options, forfeited (in shares)		(67,033)
Options, outstanding, end of period (in shares)		1,060,127
Options, vested and expected to vest (in shares)		962,331
Options, exercisable (in shares)		468,437
Weighted Average Exercise Price
Weighted average exercise price, beginning of period (per share)	$ 80.04	$ 80.04
Weighted average exercise price, granted (per share)		53.42
Weighted average exercise price, exercised (per share)		40.59
Weighted average exercise price, expired (per share)		79.76
Weighted average exercise price, forfeited (per share)		73.84
Weighted average exercise price, end of period (per share)		69.38
Weighted average exercise price, vested and expected to vest (per share)		70.58
Weighted average exercise price, exercisable (per share)		$ 81.88
Weighted average remaining contractual term (in years)		6 years 11 months 20 days
Weighted average remaining contractual term, vested and expected to vest (in years)	6 years 8 months 16 days
Weighted average remaining contractual term, exercisable (in years)		3 years 9 months 10 days
Options, outstanding, intrinsic value		$ 0.0
Options, vested and expected to vest, intrinsic value	$ 0.0
Options, vested and expected to vest, exercisable		$ 0.0