Fair Value Measurement - Summary of Long Term Restricted Marketable Securities Component and Workers' Compensation Deposits (Detail) (Available-for-sale Securities [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost	$ 34,003	$ 10,378
Gross Unrealized Gains	24	15
Recorded Basis	34,027	10,393
Money Market Funds Held in Trust [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost	21,886	0
Gross Unrealized Gains	0	0
Recorded Basis	21,886	0
Fair Value Category	1
Municipal Bonds [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost	4,928	4,742
Gross Unrealized Gains	16	10
Recorded Basis	4,944	4,752
Fair Value Category	2
Corporate Bonds [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost	2,922	2,849
Gross Unrealized Gains	8	5
Recorded Basis	2,930	2,854
Fair Value Category	2
U.S. Treasuries [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost	4,267	2,787
Gross Unrealized Gains	0	0
Recorded Basis	$ 4,267	$ 2,787
Fair Value Category	1