Stock-Based Compensation and Other Employee Benefit Plans (Narrative) (Detail) (USD $)	12 Months Ended						12 Months Ended					12 Months Ended		3 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Restricted Stock [Member]	Dec. 31, 2012 2011 Employee Stock Purchase Plan [Member]	Jul. 02, 2011 2011 Employee Stock Purchase Plan [Member]	Dec. 31, 2012 401(K) Plan [Member]	Dec. 31, 2011 401(K) Plan [Member]	Dec. 31, 2010 401(K) Plan [Member]	Dec. 31, 2012 Deferred Compensation Plan [Member]	Dec. 31, 2011 Deferred Compensation Plan [Member]	Dec. 31, 2012 Minimum [Member] 401(K) Plan [Member]	Dec. 31, 2012 Minimum [Member] Deferred Compensation Plan [Member]	Dec. 31, 2012 Maximum [Member] 2011 Employee Stock Purchase Plan [Member]	Dec. 31, 2012 Maximum [Member] 401(K) Plan [Member]	Dec. 31, 2012 Maximum [Member] Deferred Compensation Plan [Member]	Dec. 31, 2012 Noncurrent [Member] Deferred Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for purchase						1,000,000
Shares available for grant					3,947,895
Unearned compensation				$ 8,300,000
Unearned compensation, weighted average expected recognition period, in years				2 years
Total intrinsic value of vested restricted share awards	7,300,000	11,100,000	1,200,000
Intrinsic value of options exercised	5,100,000	10,300,000	800,000
Proceeds from stock option exercises	3,700,000	11,600,000	2,600,000
Employer matching contribution, percent												1.00%	1.00%		2.50%	2.50%
Maximum annual contribution per employee, amount															2,500	2,500
401(K) plan description							Subject to certain dollar limits, eligible employees may contribute up to 75% of their pre-tax annual compensation to the 401(k) plan. Effective January 1, 2011, MasTec increased its 100% match of employee contributions from 1% to 2.5% of the employee’s salary, capped at $2,500 per employee. Effective January 1, 2011, matching contributions are payable annually, 50% in shares of MasTec common stock and 50% in cash.
Employer matching contributions							2,100,000	1,700,000	800,000
Deferred compensation plan description										These employees are allowed to contribute a percentage of their pre-tax annual compensation to the deferred compensation plan. Effective January 1, 2011, MasTec increased its 100% match of employee contributions from 1% to 2.5% of the employee’s salary, capped at $2,500 per employee. Effective January 1, 2011, matching contributions are payable annually. Currently, management intends to provide for matching contributions in cash, however, matching contributions can also be provided for 50% in shares of MasTec common stock and 50% in cash, at MasTec’s election.
Deferred compensation plan assets											2,600,000						3,200,000
Deferred compensation plan liabilities										$ 3,300,000	$ 2,200,000
Employee stock purchase plan description					Under the 2011 ESPP, eligible employees can purchase MasTec, Inc. common stock at a 15% discount through after-tax payroll deductions, allocating from 1% to 15% of their compensation each pay period. Eligible employees can also make lump sum purchases. Stock purchases under the 2011 ESPP are subject to a quarterly maximum of 5,000 shares per employee, and on an annual basis, the value of stock purchased cannot exceed $25,000 per employee.
Common stock purchase discount					15.00%
Maximum number of shares per employee per quarter														5,000