Notes Payable and Long-Term Debt, Convertible Senior Notes (Details) $ in Thousands	1 Months Ended	9 Months Ended
	Jul. 31, 2019 USD ($) shares $ / shares	Sep. 30, 2019 USD ($)
Notes Payable and Long-Term Debt [Abstract]
Strike price (in dollars per share) | $ / shares	53.86
Cap price (in dollars per share) | $ / shares	82.86
Payment for cost of capped call transactions	$ 20,530
2.5% Convertible Senior Notes [Member]
Notes Payable and Long-Term Debt [Abstract]
Face amount	$ 172,500
Interest rate	2.50%	2.50%
Maturity date		Jul. 15, 2024
Shares issued upon conversion (in shares) | shares	3,202,808
Conversion rate	18.567
Conversion price (in dollars per share) | $ / shares	$ 53.86
Principal amount of notes to be converted	$ 1
Carrying value of equity component		$ 3,100
Effective interest rate		6.15%
Interest cost		$ 900
Amortization of debt discount		$ 100