CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 332,877	$ 277,766
Accounts receivable and unbilled, net (includes $2.2 million and $2.6 million with related parties at March 31, 2021 and December 31, 2020, respectively)	159,997	160,962
Prepaid expenses and other current assets	40,506	34,923
Total current assets	533,380	473,651
Property and equipment, net	84,504	85,017
Operating lease right-of-use assets	112,266	113,809
Goodwill	662,396	662,396
Intangible assets, net	45,196	46,474
Deferred income taxes	556	536
Other assets	13,062	8,794
Total assets	1,451,360	1,390,677
Current liabilities:
Accounts payable (includes $0.1 million and $0.2 million with related parties at March 31, 2021 and December 31, 2020, respectively)	21,348	26,552
Accrued expenses	123,608	134,367
Advanced billings (includes $6.1 million and $6.5 million with related parties at March 31, 2021 and December 31, 2020, respectively)	277,807	255,664
Other current liabilities	24,543	23,527
Total current liabilities	447,306	440,110
Operating lease liabilities	114,144	115,143
Deferred income tax liability	14,876	13,551
Other long-term liabilities	16,107	16,094
Total liabilities	592,433	584,898
Commitments and contingencies (see Note 11)
Shareholders’ equity:
Preferred stock - $0.01 par-value; 5,000,000 shares authorized; no shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively	0	0
Common stock - $0.01 par-value; 250,000,000 shares authorized at March 31, 2021 and December 31, 2020, respectively; 35,926,158 and 35,519,989 shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively	359	355
Treasury stock - 185,000 shares at March 31, 2021 and December 31, 2020, respectively	(5,578)	(5,578)
Additional paid-in capital	707,877	695,904
Retained earnings	158,535	115,229
Accumulated other comprehensive loss	(2,266)	(131)
Total shareholders’ equity	858,927	805,779
Total liabilities and shareholders’ equity	$ 1,451,360	$ 1,390,677

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).