Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2017

Fair Value Measurements [Abstract]

Assets and Liabilities Measured at Fair Value on a Recurring Basis

	As of June 30, 2017								As of December 31, 2016
	Fair Value Hierarchy								Fair Value Hierarchy
(in thousands)	Total		Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3
Cash and cash equivalents (a)	$	172,927	$	172,927	$	—	$	—	$	146,103	$	146,103	$	—	$	—
Restricted cash (a)		52,051		52,051		—		—		50,504		50,504		—		—
Investments in lieu of retainage (b)		56,024		52,992		3,032		—		51,266		46,855		4,411		—
Restricted investments (c)		9,281		—		9,281		—		—		—		—		—
Total	$	290,283	$	277,970	$	12,313	$	—	$	247,873	$	243,462	$	4,411	$	—

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(a)Includes money market funds with original maturity dates of three months or less.

(b)Investments in lieu of customer retainage are included in accounts receivable and are comprised of money market funds and municipal bonds, the majority of which are rated A3 or better. The fair values of the money market funds are measured using quoted market prices; therefore, they are classified as Level 1 assets. The fair values of municipal bonds are measured using readily available pricing sources for comparable instruments; therefore, they are classified as Level 2 assets.

(c)Restricted investments are held as collateral to secure our insurance related contingent obligations. The balances of these investments are held to maturity and are carried at their amortized cost of $9.3 million, which are included in other current assets. These restricted investments are comprised of various corporate bonds and bank notes which are rated A2 or better. The fair values of the corporate bonds and bank notes are measured using readily available sources for comparable instruments; therefore, they are classified as Level 2 assets.