Debt - Additional Information 1 (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Debt Instrument [Line Items]
Revolving credit facility, description of Term loan	A revolving loan component of $425.0 million, interest at a floating rate equal to, at the Company’s option, either: (1) reserve adjusted LIBOR, plus a spread that ranges from, depending on the Company’s cash flow leverage ratio, 250 to 300 basis points for the five-year tranches and 200 to 250 basis points for the three-year tranche; or (2) Alternate Base Rate, plus a spread that ranges from, depending on the Company’s cash flow leverage ratio, 150 to 200 basis points for the five year tranches and 100 to 150 basis points for the three-year tranche. “Alternate Base Rate,” as defined in the agreement, means the highest of (i) the per annum rate which the administrative agent publicly announces from time to time as its prime lending rate, as in effect from time to time, (ii) the federal funds effective rate from time to time, plus 0.5% and (iii) reserved adjusted LIBOR determined on a daily basis for a one month interest period, plus 1.0%;
Minimum [Member] | Five-year tranche, One [Member]
Debt Instrument [Line Items]
Basis spread on variable rate for the five-year tranches, One	2.50%
Minimum [Member] | Five-year tranche, Two [Member]
Debt Instrument [Line Items]
Basis spread on variable rate for the five-year tranches, One	1.50%
Term loan one [Member]
Debt Instrument [Line Items]
Revolving credit facility, description of Term loan	A $100.0 million five-year term loan, interest at a floating rate equal to, at the Company’s option, either: (1) reserve adjusted LIBOR, plus a spread that ranges from 250 to 300 basis points, depending on the Company’s cash flow leverage ratio; or (2) Alternate Base Rate, plus a spread that ranges from 150 to 200 basis points, depending on the Company’s cash flow leverage ratio. Principal amortizes $1.3 million in 2012, $5.0 million in 2013, $5.6 million in 2014, $8.1 million in 2015, $10.0 million in 2016, $5.0 million in 2017 with the remaining principal due at the end of the term;
Debt instrument base rate period	5 years
Provisions of debt obligation of revolving loan, One	$ 100.0
Principal amount amortized, 2012	1.3
Principal amount amortized, 2013	5.0
Principal amount amortized, 2014	5.6
Principal amount amortized, 2015	8.1
Principal amount amortized, 2016	10.0
Principal amount amortized, 2017	5.0
Term loan one [Member] | Minimum [Member] | Five-year tranche, One [Member]
Debt Instrument [Line Items]
Basis spread on variable rate for the five-year tranches, One	2.50%
Term loan one [Member] | Minimum [Member] | Five-year tranche, Two [Member]
Debt Instrument [Line Items]
Basis spread on variable rate for the five-year tranches, One	1.50%
Term loan one [Member] | Maximum [Member] | Five-year tranche, One [Member]
Debt Instrument [Line Items]
Basis spread on variable rate for the five-year tranches, One	3.00%
Term loan one [Member] | Maximum [Member] | Five-year tranche, Two [Member]
Debt Instrument [Line Items]
Basis spread on variable rate for the five-year tranches, One	2.00%
Term loan two [Member]
Debt Instrument [Line Items]
Revolving credit facility, description of Term loan	A $50.0 million three-year term loan, interest at a floating rate equal to, at the Company’s option, either: (1) reserve adjusted LIBOR, plus a spread that ranges from 200 to 250 basis points, depending on the Company’s cash flow leverage ratio; or (2) Alternate Base Rate, plus a spread that ranges from 100 to 150 basis points, depending on the Company’s cash flow leverage ratio. Principal amortizes $0.6 million in 2012, $2.5 million in 2013, $2.8 million in 2014, $2.8 million in 2015 with the remaining principal due at the end of the term;
Provisions of debt obligation of revolving loan, One	50.0
Principal amount amortized, 2012	0.6
Principal amount amortized, 2013	2.5
Principal amount amortized, 2014	2.8
Principal amount amortized, 2015	$ 2.8
Term loan two [Member] | Minimum [Member] | Five-year tranche, One [Member]
Debt Instrument [Line Items]
Basis spread on variable rate for the five-year tranches, One	2.00%
Term loan two [Member] | Minimum [Member] | Five-year tranche, Two [Member]
Debt Instrument [Line Items]
Basis spread on variable rate for the five-year tranches, One	1.00%
Term loan two [Member] | Maximum [Member] | Five-year tranche, One [Member]
Debt Instrument [Line Items]
Basis spread on variable rate for the five-year tranches, One	2.50%
Term loan two [Member] | Maximum [Member] | Five-year tranche, Two [Member]
Debt Instrument [Line Items]
Basis spread on variable rate for the five-year tranches, One	1.50%