Stock-based Compensation - Restricted Stock and Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Weighted Average Grant Date Fair Value
Compensation expense	$ 5,417	$ 6,493	$ 11,637	$ 14,348
Restricted Stock
Changes in unvested restricted stock
Unvested restricted shares, beginning of period (in shares)			581,408
Issued (in shares)			283,319
Vested (in shares)			(243,587)
Forfeited (in shares)			(105,009)
Unvested restricted shares, end of period(in shares)	516,131		516,131		581,408
Weighted Average Grant Date Fair Value
Balance, beginning of period			$ 24.03
Issued (in dollars per share)			27.91
Vested (in dollars per share)			22.65
Forfeited (in dollars per share)			24.07
Balance, ending of period	$ 26.60		$ 26.60		$ 24.03
Unrecognized stock-based compensation expense	$ 12,000		$ 12,000
Period for recognition			3 years
Stock options
Weighted Average Grant Date Fair Value
Unrecognized stock-based compensation expense	$ 40,000		$ 40,000
Period for recognition			2 years 9 months 18 days
Changes in unvested stock options
Outstanding, beginning of period (in shares)			4,358,291
Granted (in shares)			1,228,749
Exercised (in shares)			(589,020)
Cancelled (in shares)			(1,018,295)
Outstanding, end of period (in shares)	3,979,725		3,979,725		4,358,291
Exercisable (in shares)	1,367,908		1,367,908
Outstanding, beginning of period (in dollars per share)			$ 25.40
Granted (in dollars per share)			27.84
Exercised (in dollars per share)			16.78
Cancelled (in dollars per share)			30.83
Outstanding, end of period (in dollars per share)	$ 26.04		26.04		$ 25.40
Exercisable (in dollar per share)	$ 23.94		$ 23.94
Remaining contractual life			8 years		7 years 4 months 24 days
Exercisable, remaining contractual life			6 years 8 months 12 days
Aggregate intrinsic value	$ 17,695		$ 17,695		$ 26,060
Exercisable, aggregated intrinsic value	$ 10,035		$ 10,035