Commitments and Contingencies - Additional Information (Detail) (USD $)	1 Months Ended	6 Months Ended
	Oct. 31, 2011	Jun. 30, 2012	Dec. 31, 2011
Commitments and Contingencies [Line Items]
Rate of equity interest in Smarsh, Inc.	60.00%
Non-controlling interest, percentage	40.00%
Maximum redemption value payable		$ 22,000,000
Redeemable non-controlling interest, percentage		20.00%
Carrying amount of the redeemable non-controlling interest		22,000,000	22,000,000
Expenses incurred in construction		101,834,000	94,602,000
Land
Commitments and Contingencies [Line Items]
Expenses incurred in construction		5,200,000
Construction In Progress - Building
Commitments and Contingencies [Line Items]
Expenses incurred in construction		13,800,000
Capital expenditures		$ 10,500,000