Segment Information - Costs Incurred on Long-lived Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Segment Reporting Information [Line Items]
Costs incurred on long - lived assets	$ 437,073	$ 134,147	$ 163,261
Northeast Southeastern PA [Member]
Segment Reporting Information [Line Items]
Costs incurred on long - lived assets	14,851	9,567	16,850
Northeast Lehigh/Central PA [Member]
Segment Reporting Information [Line Items]
Costs incurred on long - lived assets	66,472	26,139	24,507
Northeast Other [Member]
Segment Reporting Information [Line Items]
Costs incurred on long - lived assets	9,232	11,974	9,370
Central Region [Member]
Segment Reporting Information [Line Items]
Costs incurred on long - lived assets	119,654	28,042	40,747
South Region [Member]
Segment Reporting Information [Line Items]
Costs incurred on long - lived assets	123,833	53,192	46,340
Metro [Member]
Segment Reporting Information [Line Items]
Costs incurred on long - lived assets	98,193	428	17,982
United Kingdom [Member]
Segment Reporting Information [Line Items]
Costs incurred on long - lived assets	$ 4,838	$ 4,805	$ 7,465