Fair Value Measurement (Tables)
 12 Months Ended
Dec. 31, 2016
Fair Value Disclosures [Abstract]  
Assets (liabilities) measured at fair value
A summary of assets (liabilities) measured at fair value is as follows:
 
As of December 31, 2016
 
Total
 
Level 1
 
Level 2
 
Level 3
Commodity contract derivatives
$
(2,239
)
 
$
(1,297
)
 
$
(942
)
 
$
—

Convertible debt conversion liability
$
(27,100
)
 
—

 
(27,100
)
 
—

Contingent consideration for acquisitions
$
(46,568
)
 
—

 
—

 
(46,568
)
 
$
(75,907
)
 
$
(1,297
)
 
$
(28,042
)
 
$
(46,568
)

 
As of December 31, 2015
 
Total
 
Level 1
 
Level 2
 
Level 3
Commodity contract derivatives
$
4,459

 
2,196

 
2,263

 
—

Contingent consideration for acquisitions
$
(41,712
)
 
—

 
—

 
(41,712
)
 
$
(37,253
)
 
$
2,196

 
$
2,263

 
$
(41,712
)
Liabilities measured at fair value on a recurring basis
The following is a reconciliation of the beginning and ending balances for liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) during the years ended as follows:
 
Contingent Consideration for Acquisitions
 
2016
 
2015
Balance at beginning of period, January 1
$
41,712

 
$
39,319

Fair value of contingent consideration at measurement date
4,500

 
5,000

Change in estimates included in earnings
7,904

 
(359
)
Settlements
(7,548
)
 
(2,248
)
Balance at end of period, December 31
$
46,568

 
$
41,712
Estimated fair values of the Company's financial instruments
The estimated fair values of the Company’s financial instruments, which are not recorded at fair value are as follows as of December 31:
 
2016
 
2015
 
Asset (Liability)
Carrying Amount
 
Estimated Fair Value
 
Asset (Liability)
Carrying Amount
 
Estimated Fair Value
Financial Liabilities:
 
 
 
 
 
 
 
Debt and lines of credit
$
(270,735
)
 
$
(264,267
)
 
$
(279,711
)
 
$
(275,123
)