Significant Accounting Policies (Details) - shares shares in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Weighted Average Number of Shares Outstanding, Basic	42,355	42,517	42,790	43,340	43,742	44,152	44,660	44,908	42,747	44,362	45,692
Incremental Common Shares Attributable to Stock Options									0	0	1
Incremental Common Shares Attributable to Contingently Issuable Shares									98	110	119
Weighted Average Number of Shares, Restricted Stock									63	128	182
Weighted Average Number of Shares Outstanding, Diluted	42,518	42,685	42,959	43,466	43,927	44,381	44,910	45,182	42,908	44,600	45,994