Income Taxes - Net Deferred Tax Assets (Detail) - USD ($)
$ in Thousands
Dec. 31, 2015
Dec. 31, 2014
Deferred Tax assets:    
Deferred customer billings $ 220,075 $ 181,567
Net operating loss carryforwards 48,201 41,654
Share-based compensation 24,995 33,895
Accrued bonus 2,008 3,791
Other reserves 606 1,019
Alternative minimum tax 1,537 1,185
Other 2,446 1,235
Fixed assets 435 0
R&D credit 189 711
Charitable contributions 534 514
Stock warrants 101 127
Total gross deferred tax assets 301,127 265,698
Less valuation allowance (302) (299)
Net deferred tax assets 300,825 265,399
Deferred tax liabilities:    
Goodwill and fixed assets 0 (817)
Total deferred tax liability 0 (817)
Net deferred tax asset $ 300,825 $ 264,582