Weighted Average Assumptions Used to Calculate Fair Value of Options Granted (Detail)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	[1]	0.00%	[1]	0.00%	[1]
Risk-free interest rate	0.70%	[2]	0.60%	[2]	1.30%	[2]
Expected volatility	33.30%	[3]	31.90%	[3]	36.90%	[3]
Expected life (in years)	3 years 7 months 6 days	[4]	4 years 7 days	[4]	4 years 11 days	[4]
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	[1],[5]	0.00%	[1],[5]	0.00%	[1],[5]
Risk-free interest rate	0.10%	[2],[5]	0.40%	[2],[5]	0.40%	[2],[5]
Expected volatility	31.70%	[3],[5]	33.70%	[3],[5]	35.60%	[3],[5]
Expected life (in years)	3 months	[4],[5]	1 year 2 months 16 days	[4],[5]	1 year 15 days	[4],[5]

[1] The Company currently has no history or expectation of paying cash dividends on its common stock in the near future.

[2] The risk-free interest rate is based on the U.S. Treasury yield for a term consistent with the expected term of the awards in effect at the time of grant.

[3] The Company estimates the volatility of its common stock at the date of grant based on the implied volatility of publicly traded options on its common stock, with a term of one year or greater.

[4] The expected life of stock options granted under the Plans is based on historical exercise patterns, which the Company believes are representative of future behavior. New grants issued by the Company had an expected life of 4.25 years in 2011, 4.00 years in 2012, and 2.58 years in 2013. Options assumed in acquisitions had expected lives of less than 4 years.

[5] Assumptions for the Employee Stock Purchase Plan relate to the annual average of the enrollment periods. During the year ended December 31, 2012, enrollment was permitted in May and November of each year. Beginning in 2013, enrollment was permitted in February, May, August, and November of each year.