Benefit Plans	12 Months Ended
Dec. 31, 2012
Compensation and Retirement Disclosure [Abstract]
Pension and Other Postretirement Benefits Disclosure	Benefit Plans: Sterling maintains an employee savings plan under Section 401(k) of the Internal Revenue Code. Substantially all employees are eligible to participate in the plan subject to certain requirements. Under the plan, employees may elect to contribute up to 10% of their salary, and Sterling will make a matching contribution equal to 35% of the employee's contribution. Each employee may make a supplemental contribution of an additional 65% of their salary. All employee contributions vest immediately and, if applicable, employer contributions vest over the employee's first three years of employment. Employees have the option of investing their contributions among selected mutual funds and Sterling common stock. Sterling contributed $2.9 million during 2012 and $2.8 million during 2011 and 2010 to the employee savings plan. Since 2002, Sterling has a supplemental executive retirement plan ("SERP"). The SERP is a nonqualified, unfunded plan that is designed to provide retirement benefits for certain key employees of Sterling. Sterling maintains and administers three additional SERPs from past acquisitions. These SERPs are all nonqualified, unfunded plans that were designed to provide retirement benefits for certain key employees and directors of the acquired companies. All amounts and benefits were established and accrued at acquisition either by previous service or change of control clauses. Sterling continues to administer these benefit plans, as necessary. Sterling had recognized $530,000, $531,000, and $505,000 for the years ended December 31, 2012, 2011 and 2010 in expenses related to the SERP. As of both December 31, 2012 and 2011, Sterling had $8.4 million accrued for the SERP. In 2006, Sterling adopted a new nonqualified deferred compensation plan (the “2006 DCP”) which is primarily funded through employee deferral contributions. The 2006 DCP is designed to retain and attract key employees while serving as a vehicle to assist participants in deferring current compensation to a time when taxes may be at a more personally beneficial rate and aid in saving for long-term financial needs. Participation in the 2006 DCP is limited to Directors and a select group of management or highly compensated employees as determined by the plan Committee. No employer contributions have been made to the 2006 DCP. Sterling had $172,000, $94,000, and $132,000 of net expenses related to the 2006 DCP for the years ended December 31, 2012, 2011 and 2010, respectively. As of December 31, 2012 and 2011, Sterling had an accrued liability for the 2006 DCP of $4.3 million and $4.8 million, respectively. During 2011, Sterling initiated an Employee Stock Purchase Plan ("ESPP"). Employees are eligible to participate in the ESPP, with purchases discounted from 0% - 15% (currently at 15%) from the closing price of Sterling's common stock on the last day of the semiannual offering period. During 2012, 38,926 shares were issued under the plan, leaving 1,961,074 shares available for future purchase as of December 31, 2012.

Benefit Plans

12 Months Ended

Dec. 31, 2012

Compensation and Retirement Disclosure [Abstract]

Pension and Other Postretirement Benefits Disclosure

Benefit Plans:

Sterling maintains an employee savings plan under Section 401(k) of the Internal Revenue Code. Substantially all employees are eligible to participate in the plan subject to certain requirements. Under the plan, employees may elect to contribute up to 10% of their salary, and Sterling will make a matching contribution equal to 35% of the employee's contribution. Each employee may make a supplemental contribution of an additional 65% of their salary. All employee contributions vest immediately and, if applicable, employer contributions vest over the employee's first three years of employment. Employees have the option of investing their contributions among selected mutual funds and Sterling common stock. Sterling contributed $2.9 million during 2012 and $2.8 million during 2011 and 2010 to the employee savings plan.

Since 2002, Sterling has a supplemental executive retirement plan ("SERP"). The SERP is a nonqualified, unfunded plan that is designed to provide retirement benefits for certain key employees of Sterling. Sterling maintains and administers three additional SERPs from past acquisitions. These SERPs are all nonqualified, unfunded plans that were designed to provide retirement benefits for certain key employees and directors of the acquired companies. All amounts and benefits were established and accrued at acquisition either by previous service or change of control clauses. Sterling continues to administer these benefit plans, as necessary. Sterling had recognized $530,000, $531,000, and $505,000 for the years ended December 31, 2012, 2011 and 2010 in expenses related to the SERP. As of both December 31, 2012 and 2011, Sterling had $8.4 million accrued for the SERP.

In 2006, Sterling adopted a new nonqualified deferred compensation plan (the “2006 DCP”) which is primarily funded through employee deferral contributions. The 2006 DCP is designed to retain and attract key employees while serving as a vehicle to assist participants in deferring current compensation to a time when taxes may be at a more personally beneficial rate and aid in saving for long-term financial needs. Participation in the 2006 DCP is limited to Directors and a select group of management or highly compensated employees as determined by the plan Committee. No employer contributions have been made to the 2006 DCP. Sterling had $172,000, $94,000, and $132,000 of net expenses related to the 2006 DCP for the years ended December 31, 2012, 2011 and 2010, respectively. As of December 31, 2012 and 2011, Sterling had an accrued liability for the 2006 DCP of $4.3 million and $4.8 million, respectively.

During 2011, Sterling initiated an Employee Stock Purchase Plan ("ESPP"). Employees are eligible to participate in the ESPP, with purchases discounted from 0% - 15% (currently at 15%) from the closing price of Sterling's common stock on the last day of the semiannual offering period. During 2012, 38,926 shares were issued under the plan, leaving 1,961,074 shares available for future purchase as of December 31, 2012.