Long-Term Debt (Details) $ / shares in Units, $ in Thousands		1 Months Ended		12 Months Ended
	Jul. 16, 2013 USD ($) TradingDay $ / shares	Oct. 31, 2016 $ / shares shares	Sep. 30, 2016 shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Jul. 31, 2016 $ / shares shares	Oct. 01, 2013 USD ($) $ / shares	Jul. 31, 2013 $ / shares
Debt Instrument [Line Items]
Amortization of debt discount				$ 7,564	$ 7,148	$ 6,757
Minimum annual principal payments and repayments of the revolving advances [Abstract]
2017				44,831
2018				178,669
2019				0
2020				0
2021				0
2022 and thereafter				0
Total				$ 223,500
CareFirst Convertible Note [Member]
Debt Instrument [Line Items]
Aggregate principal of convertible notes								$ 20,000
Interest rate for notes								4.75%
Initial conversion rate (in dollars per share | $ / shares		$ 22.41						$ 22.41
Debt converted instrument shares issued (in shares) | shares		892,458
Warrants issued (in shares) | shares				39,903			630,586
Warrants weighted average exercise price (in dollars per share) | $ / shares							$ 15.61
Convertible warrants (in shares) | shares			590,683	39,903
Number of shares converted from warrants (in shares) | shares			218,162	18,104
CareFirst Convertible Note [Member] | Maximum [Member]
Debt Instrument [Line Items]
Warrants issued (in shares) | shares				1,600,000
Number of warrants (in shares) | shares				400,000
1.50% Cash Convertible Senior Notes Due 2018 [Member]
Debt Instrument [Line Items]
Aggregate principal of convertible notes	$ 150,000
Interest rate for notes	1.50%
Debt conversion ratio	51.38
Initial conversion rate (in dollars per share | $ / shares	$ 19.46
Deferred finance costs, gross	$ 3,900
Consecutive trading days	30 days
Debt instrument convertible stock price (in dollars per share) | $ / shares	$ 25.30
Payments for hedge, financing activities	$ 36,800
Amortization of debt discount				$ 7,600
Effective interest rate				5.70%
Debt instrument, unamortized discount				$ 12,100	$ 19,700
Warrants strike price (in dollars per share) | $ / shares									$ 25.95
Conversion price premium percentage									60.00%
1.50% Cash Convertible Senior Notes Due 2018 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Number of trading days | TradingDay	20