Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 82,042	$ 85,271
Accounts receivable (less allowance for doubtful accounts of $6,567 and $5,742 as of June 30, 2019 and December 31, 2018, respectively)	279,171	242,814
Prepaid expenses and other current assets	55,923	50,136
Income tax receivable	2,996	25,299
Total current assets	420,132	403,520
Property and equipment, net	448,617	456,497
Operating lease assets	61,910	0
Goodwill, net	2,395,412	2,391,954
Other intangible assets, net	401,071	468,405
Capitalized data and database costs, net	325,060	324,049
Investment in affiliates, net	22,284	22,429
Other assets	76,026	102,136
Total assets	4,150,512	4,168,990
Current liabilities:
Accounts payable and other accrued expenses	152,394	166,258
Accrued salaries and benefits	67,795	84,940
Contract liabilities, current	320,580	308,959
Current portion of long-term debt	90,115	26,935
Operating lease liabilities, current	16,473	0
Total current liabilities	647,357	587,092
Long-term debt, net of current	1,667,021	1,752,241
Contract liabilities, net of current	524,650	524,069
Deferred income tax liabilities	105,364	124,968
Operating lease liabilities, net of current	80,268	0
Other liabilities	172,360	180,122
Total liabilities	3,197,020	3,168,492
Stockholders' equity:
Preferred stock, $0.00001 par value; 500 shares authorized, no shares issued or outstanding	0	0
Common stock, $0.00001 par value; 180,000 shares authorized; 80,133 and 80,092 shares issued and outstanding as of June 30, 2019 and December 31, 2018, respectively	1	1
Additional paid-in capital	146,887	160,870
Retained earnings	971,490	975,375
Accumulated other comprehensive loss	(164,886)	(135,748)
Total stockholders' equity	953,492	1,000,498
Total liabilities and equity	$ 4,150,512	$ 4,168,990