Long-Term Debt - Schedule of Long-Term Debt Interest Rate (Detail)	9 Months Ended
	Sep. 30, 2013
Less than .25 to 1 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Outstanding Borrowings to Borrowing Base	0.25
Less than .25 to 1 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	1.50%
Less than .25 to 1 [Member] | ABR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	0.00%
Greater than or equal to .25 to 1 but less than .50 to 1 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Outstanding Borrowings to Borrowing Base	0.5
Greater than or equal to .25 to 1 but less than .50 to 1 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Ratio of Total Outstanding Borrowings to Borrowing Base	0.25
Greater than or equal to .25 to 1 but less than .50 to 1 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	1.75%
Greater than or equal to .25 to 1 but less than .50 to 1 [Member] | ABR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	0.25%
Greater than or equal to .50 to 1 but less than .75 to 1 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Outstanding Borrowings to Borrowing Base	0.75
Greater than or equal to .50 to 1 but less than .75 to 1 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Ratio of Total Outstanding Borrowings to Borrowing Base	0.5
Greater than or equal to .50 to 1 but less than .75 to 1 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	2.00%
Greater than or equal to .50 to 1 but less than .75 to 1 [Member] | ABR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	0.50%
Greater than or equal to .75 to 1 but less than .90 to 1 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Outstanding Borrowings to Borrowing Base	0.9
Greater than or equal to .75 to 1 but less than .90 to 1 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Ratio of Total Outstanding Borrowings to Borrowing Base	0.75
Greater than or equal to .75 to 1 but less than .90 to 1 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	2.25%
Greater than or equal to .75 to 1 but less than .90 to 1 [Member] | ABR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	0.75%
Greater than .90 to 1 but less than or equal 1 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Ratio of Total Outstanding Borrowings to Borrowing Base	0.9
Greater than .90 to 1 but less than or equal 1 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	2.50%
Greater than .90 to 1 but less than or equal 1 [Member] | ABR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	1.00%