Credit Agreement (Details) (USD $)	3 Months Ended			1 Months Ended		1 Months Ended		3 Months Ended	1 Months Ended	3 Months Ended		1 Months Ended			1 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	May 31, 2013 2013 Credit Agreement	Mar. 31, 2014 2013 Credit Agreement	May 31, 2013 2013 Credit Agreement Minimum	May 31, 2013 2013 Credit Agreement Maximum	Mar. 31, 2014 2011 Credit Agreement	May 31, 2013 Health Data Insights, Inc 2011 Credit Agreement	Mar. 31, 2014 Revolving credit facility	Mar. 31, 2013 Revolving credit facility	May 31, 2013 Revolving credit facility 2013 Credit Agreement Minimum	May 31, 2013 Revolving credit facility 2013 Credit Agreement Maximum	May 31, 2013 Revolving credit facility 2011 Credit Agreement	May 31, 2013 Revolving credit facility LIBOR Rate 2013 Credit Agreement	May 31, 2013 Revolving credit facility LIBOR Rate 2011 Credit Agreement Minimum	May 31, 2013 Revolving credit facility LIBOR Rate 2011 Credit Agreement Maximum	May 31, 2013 Revolving credit facility Base rate 2013 Credit Agreement	May 31, 2013 Revolving credit facility Prime rate 2013 Credit Agreement	May 31, 2013 Revolving credit facility Federal funds rate 2013 Credit Agreement	May 31, 2013 Revolving credit facility One-month LIBOR Rate 2013 Credit Agreement	May 31, 2013 Revolving credit facility One-month LIBOR Rate 2013 Credit Agreement Minimum	May 31, 2013 Revolving credit facility One-month LIBOR Rate 2013 Credit Agreement Maximum
Credit agreement
Period of revolving credit facility				5 years					5 years
Principal borrowing capacity				$ 500,000,000										$ 500,000,000
Amount of incremental credit facilities under specified circumstances				75,000,000
Additional amount of incremental credit facilities under specified circumstances						25,000,000
Secured leverage ratio							2.5
Consolidated leverage ratio before reduction							3.50
Maximum consolidated leverage ratio							3.25
Reduction period of maximum consolidated leverage ratio				5 years
Minimum interest coverage ratio						3.00
Interest rate of debts															LIBOR			Base Rate	Prime Rate	Federal funds rate	one-month LIBOR
Interest rate margin (as a percent)																1.50%	2.25%			0.50%	1.00%	0.50%	1.25%
Unused commitment fee on the revolving credit facility of the credit agreement (as a percent)												0.375%	0.50%
Outstanding principal repaid		8,750,000						323,800,000
Unpaid interest paid	1,188,000	2,879,000						1,100,000
Loan origination fees					2,900,000
Interest expense										1,164,000	2,662,000
Commitment fees										328,000	117,000
Unamortized balance of deferred origination fees and debt issue costs	8,500,000		9,000,000
Amortization of financing cost	500,000	900,000
Irrevocable letter of credit or Letter of Credit outstanding	$ 4,600,000