Redeemable Preferred Stock - Additional Information (Detail) (USD $)	12 Months Ended				1 Months Ended			1 Months Ended	12 Months Ended			12 Months Ended
	Dec. 31, 2012	Sep. 25, 2012	Dec. 31, 2011	Sep. 16, 2011	Sep. 16, 2011 CMP Acquisition	Sep. 16, 2011 CMP Acquisition	Sep. 16, 2011 CMP Acquisition CMP Preferred Stock	Sep. 15, 2011 Series A Redeemable Preferred Stock	Dec. 31, 2012 Series A Redeemable Preferred Stock	Dec. 31, 2011 Series A Redeemable Preferred Stock	Sep. 16, 2011 Series A Redeemable Preferred Stock	Dec. 31, 2012 Series A Redeemable Preferred Stock Scenario 1	Dec. 31, 2012 Series A Redeemable Preferred Stock Scenario 2
Class of Stock [Line Items]
Preferred stock, shares authorized				100,000,000				2,000,000	100,000,000	100,000,000
Preferred stock, par/stated value	$ 0.01		$ 0.01	$ 0.01				$ 0.01	$ 1,000	$ 1,000
Liquidation preference								$ 1,000
Preferred stock, shares issued								125,000	75,767	125,000	125,000
Preferred Stock								$ 125,000,000
Net proceeds to the Company								110,700,000
Preferred stock issuance fee								14,300,000
Percentage of unpaid dividends that may be paid with additional shares of Series A Preferred Stock									50.00%
Rate of Dividend accrual through March 15, 2012									10.00%
Rate of Dividend accrual through September 15, 2013									14.00%
Rate of Dividend accrual from September 16, 2013 to September 15, 2015									17.00%
Rate of Dividend accrual after September 16, 2015									20.00%
Redemption terms of series A preferred stock									Redemption price equal to the lesser of (1) an amount equal to 100% of such net cash proceeds and (2) the $125.0 million aggregate par value of the Series A Preferred Stock plus any accrued but unpaid dividends.
Redemption terms of series A preferred stock, percentage of issue price												100.00%
Redemption terms of series A preferred stock, aggregate par value													125,000,000
Fair value of preferred stock assumed in acquisition		16,800,000	17,394,000				41,069,000
Par value of CMP preferred stock	32,800,000				32,700,000
Cumulative undeclared dividends on CMP preferred stock	8,300,000				8,300,000
Dividends paid					500,000	500,000			15,000,000	500,000
Series A cumulative redeemable preferred stock	71,869,000		113,447,000		41,600,000	41,600,000			71,869,000	113,447,000
Company redeemed and retired shares									49,233
Preferred Stock									49,200,000
Unpaid dividends accrued through redemption date									800,000
Dividends accrued									13,800,000	3,600,000
Dividends paid on redeemed shares									800,000	800,000
Dividends accreted									7,700,000	2,700,000
Preferred stock outstanding									75,767	125,000
Dividends paid , first quarter of 2013									$ 2,700,000